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Title: Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, Second Part: Subclass Osculosa; Index - Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII
Author: Haeckel, Ernst, 1834-1919
Language: English
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BY H.M.S. CHALLENGER DURING THE YEARS 1873-1876, SECOND PART: SUBCLASS
OSCULOSA; INDEX***


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Note: Images of the original pages are available through
      Internet Archive. See
      https://archive.org/details/reportonradiolar02haecrich

      First Part: First Part: Porulosa (Spumellaria and Acantharia)
      Plates


Transcriber's note:

      Text enclosed by underscores is in italics (_Actissa_).

      The underscore also denotes a subscript, so _c__1 is an
      italic c with a subscript (note that there are two
      underscoreds between the "c" and the "1").

      Text enclosed by hash marks is in "gesperrt"
      (wide-spaced) type (#Larcoidea#).

      Page numbers enclosed by curly braces (example: {25}) have
      been incorporated to facilitate the use of the Index.

      Some typographical errors in the printed work have been
      corrected. They are listed at the end of the text.

      The Addenda & Errata (Second Part, pp. 1763-4) have been
      applied without further comment.



REPORT ON THE SCIENTIFIC RESULTS OF THE VOYAGE OF H.M.S. CHALLENGER
DURING THE YEARS 1873-76

Under the Command of Captain George S. Nares, R.N., F.R.S.
and the Late Captain Frank Tourle Thomson, R.N.

Prepared Under the Superintendence of
the Late Sir C. Wyville Thomson, KNT., F.R.S., &c.
Regius Professor of Natural History in the University of Edinburgh
Director of the Civilian Scientific Staff on Board
and Now of
John Murray
One of the Naturalists of the Expedition

ZOOLOGY--VOL. XVIII.

SECOND PART

Published by Order of Her Majesty's Government



Printed for Her Majesty's Stationary Office
and Sold by
London:--Eyre & Spottiswoode, East Harding Street, Fetter Lane
Edinburgh:--Adam & Charles Black
Dublin:--Hodges, Figgis, & Co.
1887

Price (in Two Parts, with a Volume of Plates) £5, 10s.



CONTENTS.



REPORT on the RADIOLARIA collected by H.M.S. CHALLENGER during the years
1873-1876.

By ERNST HAECKEL, M.D., Ph.D., Professor of Zoology in the University of
Jena.

SECOND PART.--OSCULOSA.

(#NASSELLARIA AND PHÆODARIA.#)



CONTENTS.



  SECOND PART.

    II. Subclass OSCULOSA,                                      889
          Legion III. NASSELLARIA vel MONOPYLEA,                889
               Order 11. Nassoidea,                             895
                 "   12. Plectoidea,                            898
                 "   13. Stephoidea,                            931
                 "   14. Spyroidea,                            1015
                 "   15. Botryodea,                            1103
                 "   16. Cyrtoidea,                            1126

          Legion IV. PHÆODARIA vel CANNOPYLEA,                 1521
               Order 17. Phæocystina,                          1542
                 "   18. Phæosphæria,                          1590
                 "   19. Phæogromia,                           1642
                 "   20. Phæoconchia,                          1710

  Note on the Dimensions and Measurements,                     1760

  ADDENDA,                                                     1761

  ERRATA,                                                      1763

  INDEX,                                                       1765



{889}LEGION III. NASSELLARIA,

VEL MONOPYLEA, VEL MONOPYLARIA (PLS. 51-98).

  _Nassellaria_ (_inclusis_ Spyridinis), Ehrenberg, 1875.
  _Monopylea_, Hertwig, 1879.
  _Monopylaria_, Haeckel, 1881.
  _Cyrtida_ et _Acanthodesmida_, Haeckel, 1862.
  _Cricoidea_, Bütschli, 1882 (L. N. 40, p. 537) = NASSELLARIA.

_Definition._--Radiolaria with simple membrane of the central capsule,
which is monaxon or bilateral, and bears on one pole of the main axis a
porous area (porochora), forming the base of a peculiar intracapsular cone
(podoconus). Extracapsulum without phæodium. Skeleton siliceous, very
rarely wanting. Fundamental form originally monaxon, often dipleuric or
bilateral.

The legion NASSELLARIA vel MONOPYLEA, in the extent here defined, was
constituted in 1879 by Richard Hertwig in his work Der Organismus der
Radiolarien (pp. 133-137). He gave to this large group the rank of an
order, and united in it the two families Acanthodesmida and Cyrtida, which
I had constituted first in 1862 in my Monograph (pp. 237, 265, 272); but he
added, too, as a third family the Plagiacanthida, united by me with the
former. In the first system of Ehrenberg (1847, _loc. cit._, pp. 53, 54),
four families belonging to the MONOPYLEA were enumerated, the
Halicalyptrina, Lithochytrina, Eucyrtidina, and Spyridina. He united the
three former under the name "Polycystina solitaria," which he afterwards
changed into NASSELLARIA (1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p.
157).

In my Monograph of the Radiolaria (1862, pp. 265-345) forty-four genera of
NASSELLARIA were enumerated (six Acanthodesmida and thirty-eight Cyrtida),
whilst the total number of genera in the whole class of Radiolaria at that
time amounted to one hundred and thirteen. But owing to the astonishing
number of new and interesting forms of this legion which I afterwards
detected in the collection of the Challenger, in 1881 I distinguished in my
Prodromus not less than three hundred and seventeen genera. These were
disposed in five large main groups, retained in the present Report, with
twenty-six families, viz., (1) #Plectoidea# (with three families), (2)
#Stephoidea# (with four families), (3) #Spyroidea# (with four families),
(4) #Botryodea# (with three families), and (5) #Cyrtoidea# (with twelve
families). The first two groups have an incomplete or rudimentary skeleton,
and may be united in the order #Plectellaria#, whilst the other three
families possess a complete latticed shell, and {890}may be united as
#Cyrtellaria#. The former correspond to the Acanthodesmida, the latter to
the Cyrtida in my Monograph.

The character common to all MONOPYLEA or NASSELLARIA, which separates them
from all other Radiolaria, was first recognised by Richard Hertwig in 1879,
and consists in the singular structure of the monaxonian central capsule,
bearing on the basal pole a peculiar porous area or operculum, the
"Porenfeld;" we call it shortly the "porochora." It represents a circular
or elliptical porous plate on the basal pole of the vertical main axis of
the central capsule, and bears a peculiar "podoconus" or
"Pseudopodien-Kegel," a conical body of singular structure, protruding
inside the membrane into the capsule. The pseudopodia arising from this
peculiar "podoconus" proceed from the capsule piercing the "porochora,"
whilst the other parts of the capsule are not perforated.

The MONOPYLEA are therefore "Merotrypasta," like the following fourth
legion, the PHÆODARIA or CANNOPYLEA. But in these latter we find on the
basal pole of the monaxonian capsule only one single large main opening,
prolonged into a peculiar tube, and there is no trace of the typical
"podoconus," characteristic of all NASSELLARIA. The latter agree, however,
with the former in the possession of a basal opening, serving for the
emission of the pseudopodia, and in the monaxonian fundamental form,
arising from this structure. Therefore these two legions of "Merotrypasta"
exhibit a wider divergence from the ACANTHARIA and SPUMELLARIA, the two
legions of "Holotrypasta," in which the central capsule is everywhere
perforated by innumerable small pores (compare above, pp. 5, 6, 716).

_The Skeleton_ in all NASSELLARIA consists either of pure silica, or of a
peculiar silicate; never of acanthin (as in all ACANTHARIA). The siliceous
bars and beams constituting it are invariably solid (as also in the
SPUMELLARIA); never hollow (as in the PHÆODARIA). In the small family of
Nassellida alone (with the two genera _Cystidium_ and _Nassella_) the
skeleton is entirely absent. In all other genera of NASSELLARIA the
siliceous skeleton is more or less developed; imperfect, or quite
rudimentary in the #Plectellaria# (#Plectoidea# and #Stephoidea#), but
perfect and forming a regular lattice-shell in the #Cyrtellaria#
(#Spyroidea#, #Botryodea#, and #Cyrtoidea#). The different forms of this
skeleton exhibit an extraordinary variety, but may be reduced to a few very
simple fundamental forms, or even to a single, most simple original form.
The comparative morphology is more interesting, but also more difficult to
understand than in any other Radiolaria.

The geometrical fundamental form of the skeleton is in all NASSELLARIA
monaxonial, the vertical main axis of the body, which is already indicated
by the axis of the central capsule with two different poles, being also
expressed constantly in the form of the skeleton. The lower or basal pole
of the latter always exhibits a different shape from that of the upper or
apical pole. This difference is so striking in nearly all MONOPYLEA, that
the two poles may be determined on the first view.

{891}In the great majority of NASSELLARIA not only is the monaxonial
fundamental form expressed, but also the dipleuric or bilateral, so that
the symmetrical halves of the body may be easily determined; the right and
left halves exhibit the same symmetry as in the vertebrates, so that we may
distinguish an anterior ventral and a posterior dorsal face of the body.
The whole form is in this case determined by three dimensive axes,
perpendicular to one another, two of which are heteropolar, the third is
homoeopolar. The apical pole of the vertical main axis (principal or
longitudinal axis) is different from the basal pole. The ventral pole of
the horizontal sagittal axis (or dorso-ventral axis) is different from the
dorsal pole. The right pole of the horizontal transverse axis (lateral or
frontal axis) is equal to the left pole. Therefore the sagittal or median
plane of the body (in which the principal and the sagittal axis are
crossed) divides it into symmetrical equal halves and is perpendicular to
the frontal axis.

Three different original elements of structure are recognisable in the
majority of NASSELLARIA, viz., (1) a vertical simple ring, the primary or
sagittal ring, placed vertically in the sagittal plane and enclosing the
median plane of the central capsule; (2) a basal tripod, composed of three
diverging radial rods, which are united on the basal pole of the central
capsule and are either expanded horizontally or descend; (3) an ovate or
subspherical, simple lattice-shell, the cephalis or capitulum, which
surrounds the central capsule and exhibits a peculiar structure on its
basal pole.

These three important original elements of structure--the sagittal ring,
the basal tripod, and the latticed cephalis--are so united in the majority
of NASSELLARIA that the cephalis rests upon the tripod and includes the
sagittal ring wholly or partially. The simplest realisation of this typical
union is afforded by the Archiperida and Tripospyrida, and these may be
derived from the simpler important Stephanid _Cortina_ (Pl. 83, fig. 9; Pl.
92, fig. 21; Pl. 97, fig. 1). In this and in all other tripodal
NASSELLARIA, the three basal rods or the "cortinar feet" are constantly so
arranged that an odd or posterior rod, the "caudal foot" (_c_) is opposed
to the two anterior paired rods, the "pectoral feet" (one right, _p_", and
one left, _p_'). The caudal foot lies in the sagittal plane, and is
prolonged upwards into the dorsal rod of the sagittal ring (_b_), and over
this in a free ascending spine, the "apical horn" (_a_). The curved ventral
rod of the ring (_r_) is united above with the base of the apical horn,
below with the common centre of the tripod or the "cortinar centrum." The
characteristic position of the central capsule in this skeleton of
_Cortina_ is such that its basal pole (with the porochora) rests upon the
centre of the tripod, whilst its sagittal perimeter is separated from the
surrounding ring by the calymma; the numerous pseudopodia arising from its
base diverge downwards and are supported and protected by the three basal
feet of the tripod (Pl. 97, fig. 1). Compare also Pls. 51, 53, 84, 95, 98.

The typical skeleton of _Cortina_, a tripodal ring, becomes more developed
in the Semantid _Cortiniscus_, in which the basal parts of the three
diverging feet are united {892}by a second horizontal ring, the cortinar or
basal ring (Pl. 92, figs. 11-13). The pores between the former and the
latter, or the "cortinar pores," may be regarded as the first beginning of
the lattice-plate, composing the "cephalis" or the simple primordial shell
in the Archiperida and Tripospyrida, and transmitted from these by heredity
to the great majority of NASSELLARIA.

The "cephalis or capitulum" (the "Köpfchen" of the German authors) is
therefore the most important part of the skeleton in all #Cyrtellaria#, or
in all NASSELLARIA possessing a complete lattice-shell. In the
#Plectellaria#, however, or in those NASSELLARIA which do not possess a
complete fenestrated shell, the "cephalis" is either imperfect or totally
wanting. The cephalis surrounds the enclosed central capsule on all sides
in the form of an ovate or subspherical lattice-shell, and is separated
from it only by the jelly-like calymma. The sagittal ring is either
enclosed in the wall of the cephalis (whole or partially), separating its
two lateral halves, or it is enclosed in the cavity of the cephalis and
connected with its sagittal perimeter by short beams. The base of the
cephalis (with the cortinar plate) often rests immediately upon the centre
of the tripod; in the majority of NASSELLARIA, however, this near relation
is altered by reason of later changes and secondary modifications.

The number of various forms, developed from these simple original
structural elements of the skeleton, is astonishing, and there are
described more than three hundred genera and nearly two thousand species of
this legion in the following pages. This large number may be easily
increased by subsequent observers. Since in all these MONOPYLEA the
characteristic structure of the central capsule is identical, and also the
structural elements of the siliceous skeleton are similar, it is very
probable that they may have arisen from a single common stock. But it is
very difficult (and at present impossible) to explain a natural
monophyletic system of this large legion. The greatest difficulty is
presented by the fact that the three structural elements mentioned above,
viz., the sagittal ring, the basal tripod, and the latticed cephalis, are
not constantly united, but each alone may also constitute the skeleton by
itself. In this respect the following seven cases are possible, and are
actually realised.

A. The skeleton is composed of the sagittal ring only and of its spiny
appendages, without basal tripod and without latticed cephalis. This is the
case in the majority of #Stephoidea# (Stephanida, Semantida, Coronida, and
Tympanida).

B. The skeleton is composed of a basal tripod only (_Plagiacantha_), or of
a tripod in the centre of which arises a vertical apical horn
(_Plagoniscus_), and often of an irregular framework, arising from the rods
of the tripod; but there is neither a trace of a sagittal ring nor a
complete latticed cephalis. This is the case in the remarkable suborder
#Plectoidea# (Plagonida and Plectanida).

C. The skeleton is composed of a latticed cephalis only, a simple ovate or
subspherical fenestrated shell, which encloses the monopylean central
capsule; there is no {893}trace of a sagittal ring nor of a basal tripod.
This is the case in the remarkable family of Cyrtocalpida (Archicorida and
Archicapsida), in numerous #Botryodea# and in other #Cyrtellaria#.

D. The skeleton is composed of a sagittal ring and a basal tripod, without
latticed cephalis. This is the case in a few, but very important forms of
#Stephoidea#: _Cortina_, _Stephanium_, _Cortiniscus_, _Stephaniscus_,
_Podocoronis_, and some allied genera.

E. The skeleton is composed of a sagittal ring and a latticed cephalis, but
without basal tripod. This is the case in numerous #Cyrtellaria#, in the
Circospyrida (or Zygospyrida apoda: _Dictyospyris_, _Circospyris_) and some
other #Spyroidea#; and in a large number of #Botryodea# and Cyrtoidea
eradiata (a part of the Sethocyrtida, Theocyrtida, Lithocampida, and
others).

F. The shell is composed of a basal tripod and a latticed cephalis, but
without any trace of the sagittal ring. This is the case in numerous
Cyrtoidea triradiata and multiradiata, and perhaps in the majority of the
following families--Tripocalpida, Tripocyrtida, Podocyrtida, and
Podocampida.

G. The shell is composed of all three above-mentioned elements, of a
sagittal ring, a basal tripod, and a latticed cephalis. This is the case in
the great majority of #Spyroidea# (with a few exceptions only), and perhaps
also in the majority of #Cyrtoidea#.

The survey of these seven groups, A to G, each of which is represented by
numerous living forms, shows clearly how difficult and complicated the
morphology and phylogeny of the numerous NASSELLARIA must be. For all
possible combinations of the three original structural elements are
realised abundantly, and in such complicated relations, and so intermingled
in the different orders and families, that it seems nearly hopeless to
answer the question of their true origin. The identity in the structure of
the central capsule, however, in all these MONOPYLEA, makes it probable
that they have all arisen originally from the skeletonless Nassellida
(_Cystidium_, _Nassella_), either in a monophyletic or in a polyphyletic
way. In this respect the following phylogenetical hypotheses are possible.

1. Monophyletic hypothesis, deriving all NASSELLARIA from a simple sagittal
ring (_Archicircus_, _Lithocircus_, &c., Pl. 81). The groups A, D, E, and G
may be derived easily from such a ring, but the groups B, C, and F only by
means of the hypothesis that the original ring may be completely reduced
and finally lost. This hypothesis was stated by me in the years 1877 to
1879, when I had got the first general survey of the astonishing number of
new NASSELLARIA in the Challenger collection, and as I had found the
sagittal ring in the majority of them. This, my former hypothesis, is
mentioned by Richard Hertwig (1879, _loc. cit._, pp. 68, 126). It was
afterwards supported with particular energy by O. Bütschli (1882, Zeitschr.
für wiss. Zool., Bd. XXXVI.).

2. Monophyletic hypothesis, deriving all NASSELLARIA from a basal tripod
(_Triplagia_, _Plagoniscus_, &c., Pl. 91). The groups B, D, F, and G, all
triradiate, may {894}be derived easily from such a tripod; but the groups
A, C, and E only by means of the hypothesis that the original tripod may be
completely reduced and finally lost. This hypothesis was employed in 1881
in my Prodromus, since I had convinced myself that the "triradial
structure" is prevalent in the great majority of NASSELLARIA, and is
perhaps more important than the sagittal ring.

3. Monophyletic hypothesis, deriving all NASSELLARIA from a latticed
cephalis, a simple ovate or subspherical fenestrated shell without ring and
tripod (_Cyrtocalpis_, _Archicapsa_, &_c._). The groups C, E, F, and G may
be derived easily from such a cephalis, but the groups A, B, and D only by
means of the hypothesis that the sagittal ring as well as the basal tripod
may remain as the last remnants of a reduced cephalis. This hypothesis was
given in 1862 in my Monograph, where I constructed the first pedigree of
Radiolaria (p. 234). I there derived all the Cyrtida from the #Sphæroidea#
(_Cyrtidosphæra_), supposing that _Cyrtocalpis_ and some other Monocyrtida
may form a direct phylogenetical passage from the #Sphæroidea# to the
#Cyrtoidea#.

4. Polyphyletic hypothesis, deriving the different groups of NASSELLARIA
from different skeletonless Nassellida, by development of simple siliceous
skeletons in different ways. Among the numerous polyphyletic hypotheses
which are possible, one of the simplest would be the supposition that three
different fundamental forms of skeleton may have arisen independently one
from another: (1) a simple sagittal ring as original form of the
#Stephoidea# and #Spyroidea# (A); (2) a simple basal tripod as original
form of the #Plectoidea# (B); (3) a simple latticed cephalis as original
form of the #Botryodea# and #Cyrtoidea# (C). This triphyletic hypothesis is
supported by R. Hertwig (1879, _loc. cit._, p. 136); he assumes that the
original skeletonless Nassellida (_Cystidium_) have produced three
different branches, his "Acanthodesmida" (= #Stephoidea# and #Spyroidea#)
with a primary ring, his "Plagiacanthida" (= #Plectoidea#) with a primary
tripod, and his Cyrtida (= #Botryodea# and #Cyrtoidea#) with a primary
cephalis. This hypothesis seems rather probable on the first view; but it
meets with the greatest difficulties in view of the fact that these three
original elements of the skeleton are more or less evidently combined in
the great majority of NASSELLARIA. The greatest difficulty arises from the
fact that often among very similar and closely allied forms the first
exhibits all three elements (A, B, C) combined, whilst the second has a
combination of A and B, the third of B and C, the fourth of A and C; and
there are other forms, very similar to the former, in which one element
only is recognisable. Another difficulty arises from the fact that the
intimate structure of the cephalis in the majority of #Cyrtellaria# is not
perfectly known, and often exhibits structures which are difficult to
explain with regard to the three elements A, B, C. Under these
circumstances further researches on the numerous imperfectly known
NASSELLARIA are required, and chiefly accurate observations on their more
minute structure and on their important ontogeny.

{895}We divide the immense legion of NASSELLARIA into two large orders, the
#Plectellaria# without complete lattice-shell, and the #Cyrtellaria# with a
complete lattice-shell or a "cephalis," including the central capsule; the
latter, of course, have arisen from the former. The #Plectellaria# comprise
three different suborders, the #Nassoidea# (without skeleton), the
#Plectoidea# (with a tripodal skeleton, without ring), and the #Stephoidea#
(with a primary sagittal ring, with or without tripod). The #Cyrtellaria#
again also comprise three different suborders, the #Spyroidea# (with
bilocular cephalis and a sagittal constriction), the #Botryodea# (with
multilocular and lobate cephalis, exhibiting two or more constrictions and
three or more lobes), and the #Cyrtoidea# (with simple, unilocular
cephalis, without constriction).

_Synopsis of the Orders and Suborders of_ NASSELLARIA.

  I. Order                 {No skeleton,                   1. #Nassoidea#.
  PLECTELLARIA.            {
  Nassellaria without      {Skeleton with a basal tripod,
  complete lattice-shell.  {  without ring,                2. #Plectoidea#.
                           {
                           {Skeleton with a sagittal ring
                           {  (usually without tripod),    3. #Stephoidea#.

                           {Cephalis bilocular, with a
                           {  sagittal constriction,       4. #Spyroidea#.
  II. Order                {
  CYRTELLARIA.             {Cephalis multilocular, with
  Nassellaria with a       {  two or more constrictions
  complete lattice-shell.  {  and lobes,                   5. #Botryodea#.
                           {
                           {Cephalis simple, without
                           {  constriction and lobes,      6. #Cyrtoidea#.


----


Order V. PLECTELLARIA, Haeckel, 1883.

_Definition._--NASSELLARIA without complete lattice-shell, usually with an
incomplete skeleton, formed of a ring, a tripod, or an irregular framework.



Suborder I. NASSOIDEA, Haeckel.

_Definition._--NASSELLARIA without skeleton. Single family Nassellida.



{896}Family XLV. #NASSELLIDA#, Haeckel.

  _Cystidina_, Haeckel, 1883, Sitzungsb. Jena Ges. für Naturw., Februar 16.

_Definition._--NASSELLARIA without skeleton. The soft body composed of a
monopylean central capsule (with porochora and podoconus) and of a
surrounding jelly-veil or calymma.

The family #Nassellida# comprises the simplest and most primitive forms of
NASSELLARIA, the only group which is entirely without a skeleton. The
central capsule is therefore perfectly free and naked, enveloped by the
calymma only, as in the #Colloidea# among the SPUMELLARIA, in the
Phæodinida among the PHÆODARIA. Probably these naked and skeletonless
MONOPYLEA must be regarded as surviving remnants of the common ancestral
group of this legion; but the possibility is not excluded that the few
observed forms are either young NASSELLARIA which have not yet secreted a
skeleton, or older NASSELLARIA which have lost their original skeleton.

We distinguish in this small family two genera only: _Cystidium_ with
hyaline, not foamy calymma, without extracapsular alveoles, and _Nassella_,
with a very voluminous foamy calymma, including numerous large alveoles;
the former corresponds to _Actissa_ and the latter to _Thalassicolla_ among
the #Colloidea# or the skeletonless SPUMELLARIA. But in these two latter
genera, as in all PERIPYLEA, the central capsule is perforated everywhere
by innumerable small pores; the two former genera, however, exhibit the
same characteristic podoconus in the central capsule, and the same
porochora at its base, as all the other MONOPYLEA. The pseudopodia are
protruded from the central capsule through the porochora only.

_The Central Capsule_ is in the two observed genera either ovate or nearly
spherical, usually slightly tapering towards the basal mouth. Its
transverse section is constantly circular. The membrane of the capsule is
usually rather thick and double-contoured, and bears on the truncate basal
pole a circular "porochora" or area porosa, through which the pseudopodia
are protruded. The _porochora_ is either quite simple, circular, or in some
species trilobed, with three equal circular lobes, each of which is
surrounded by a girdle of small granules. The _podoconus_, or
"pseudopodial-cone," arising vertically from the horizontal basal
porochora, is half as long as the central capsule, or longer, simply
conical and finely striped longitudinally. The _nucleus_ lies usually in
the uppermost part of the central capsule, above or behind the podoconus,
and is either spherical or ovate, sometimes kidney-shaped. It includes one
or more nucleoli.

_Synopsis of the Genera of Nassellida._

  Calymma hyaline, without alveoles,             382. _Cystidium_.

  Calymma foamy, with numerous large alveoles,   383. _Nassella_.



{897}Genus 382. _Cystidium_,[1] R. Hertwig, 1879, Organismus d. Radiol., p.
87.

_Definition._--#Nassellida# with hyaline calymma, without extracapsular
alveoles.

The genus _Cystidium_ is the simplest and most primitive among all
NASSELLARIA, and may be regarded as the common ancestral form of this
legion, for which it has the same high importance as _Actissa_ for the
SPUMELLARIA. The central capsule is quite simple, ovate or nearly
spherical, and included in a voluminous hyaline calymma, which contains no
large alveoles. _Cystidium_ differs from _Actissa_, its probable ancestral
form, in the possession of the "podoconus" and its basal "porochora,"
characteristic of all NASSELLARIA or MONOPYLEA.


1. _Cystidium princeps,_ n. sp. (Pl. 91, fig. 1).

Central capsule ovate, one and a third times as long as broad. Podoconus
with simple circular porochora, about half as long as the capsule,
surrounded at its base by red granules of pigment. Nucleus spherical. Three
equal oil-globules in the endoplasm. No pigment in the voluminous calymma,
which includes numerous xanthellæ.

_Dimensions._--Length of the central capsule 0.1, breadth 0.075; nucleus
0.035.

_Habitat._--Indian Ocean, Maldive Islands (Haeckel), surface.


2. _Cystidium lecythium,_ n. sp.

Central capsule ovate, one and a half times as long as broad. Podoconus
with simple circular porochora, three-fourths as long as the capsule.
Nucleus ellipsoidal. No oil-globules in the endoplasm. No pigment and no
xanthellæ in the calymma.

_Dimensions._--Length of the central capsule 0.12, breadth 0.08; nucleus
0.04.

_Habitat._--Central Pacific, Station 271, surface.


3. _Cystidium inerme,_ R. Hertwig.

  _Cystidium inerme,_ R. Hertwig, 1879, Organismus d. Radiol., p. 87, Taf.
  vii. figs. 1-1_b_.

Central capsule subspherical, a little longer than broad. Podoconus about
two-thirds as long as the capsule, with trifid porochora, which is composed
of three equal circular lobes. Nucleus spherical. Numerous oil-globules in
the endoplasm. The calymma includes numerous xanthellæ and brown pigment
around the mouth.

_Dimensions._--Length of the central capsule 0.06, breadth 0.05; nucleus
0.03.

_Habitat._--Mediterranean, Messina (R. Hertwig), surface.



{898}Genus 383. _Nassella_,[2] nov. gen.

_Definition._--#Nassellida# with foamy calymma, containing numerous large
extracapsular alveoles.

The genus _Nassella_ differs from the preceding _Cystidium_, its probable
ancestral form, in the development of numerous large alveoles in the
extracapsular calymma, and therefore exhibits the same relation to it that
_Thalassicolla_ bears to _Actissa_ among the SPUMELLARIA. The foamy calymma
is very voluminous, and includes numerous symbiotic xanthellæ.


1. _Nassella thalassicolla_, n. sp.

Central capsule spherical. Podoconus with simple circular porochora, half
as long as the capsule. Nucleus spherical. Numerous oil-globules in the
endoplasm. Calymma spherical, without pigment, with numerous xanthellæ and
large alveoles.

_Dimensions._--Diameter of the central capsule 0.12, nucleus 0.04, calymma
0.6.

_Habitat._--South Pacific, Station 300 (off Juan Fernandez), surface.


2. _Nassella nassiterna_, n. sp.

Central capsule ovate. Podoconus two-thirds as long as the capsule, trifid,
with three equal circular lobes (as in _Cystidium inerme_). Nucleus ovate.
Three equal large oil-globules in the endoplasm, corresponding to the three
lobes of the porochora. Calymma ovate, in the upper half much more
voluminous than in the lower, including numerous large alveoli and
xanthellæ, and around the mouth masses of black pigment.

_Dimensions._--Diameter of the central capsule 0.1, nucleus 0.03, calymma
0.8.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.


----


Suborder II. PLECTOIDEA, Haeckel.

  _Plectoidea_ vel _Plectida_, Haeckel, 1881, Prodromus, p. 423.
  _Plagiacanthida_ (_sensu ampliori_), R. Hertwig, 1879, Organismus d.
      Radiol., p. 72.

_Definition._--NASSELLARIA with a rudimentary, originally tripodal
skeleton, composed of radial spines, arising from one common central point
or central rod; the spines are simple or branched, and the branches may
form by concrescence of their meeting ends a loose wickerwork, but never a
complete lattice-shell. Never a ring in the skeleton.

{899}The suborder #Plectoidea#, hitherto known by few species only of
"Plagiacanthida," comprises a large number of interesting NASSELARIA, which
belong partly to the simplest and most primitive forms of this legion. It
may be divided into two different families, Plagonida and Plectanida. In
the first family, Plagonida, the monopylean central capsule is supported by
a simple or rudimentary skeleton, composed only of a variable number of
radial spines united in a common centre. In the second family, Plectanida,
the branches of these radial spines become united and form a loose
irregular framework with wide meshes, partly enclosing the central capsule,
but never a perfect lattice-shell.

The #Plectoidea# differ from the following suborder, the #Stephoidea#, in
the absence of the ring, characteristic of the latter. Some slight traces,
however, indicate a near affinity between the ringless #Plectoidea# and the
ring-bearing #Stephoidea#. Both these suborders of #Plectellaria# differ
from the closely allied #Cyrtellaria# (#Spyroidea#, #Botryodea#, and
#Cyrtoidea#) in the absence of a complete lattice-shell. The morphological
relation and phylogenetic affinity between the former and the latter have
already been discussed in the preceding description of the legion
NASSELLARIA (compare pp. 891-894).

The first known species of #Plectoidea# was observed in the North Atlantic
(on the Norwegian shore) in 1855 by my late friend Edouard Claparède, and
described and figured in his Études, &c. (1858), under the name
_Plagiacantha arachnoides_. He considered it as a new genus of
Acanthometrina. Another species, from the Mediterranean, was described in
the same year by Johannes Müller as _Acanthodesmia dumetum_ (1858, _loc.
cit._, Taf. i. fig. 3). A third species, also Mediterranean, was figured by
me in 1865 under the name _Acanthodesmia polybrocha_. Finally, Richard
Hertwig, 1879, in his Organismus der Radiolarien, gave a very accurate
description of another Mediterranean form, _Plagiacantha abietina_ (_loc.
cit._, Taf. vii. fig. 6). He first recognised the true character of
MONOPYLEA in their monaxonian central capsule, and observed at the same
time the first NASSELLARIUM without skeleton, called by him _Cyrtidium
inerme_ (_loc. cit._, Taf. vii. fig. 1). To these four known species,
representing three different genera, the rich collection of the Challenger
has added so many new forms that we may distinguish here not less than
seventeen genera and sixty-one species. In my Prodromus (1881, p. 423) I
arranged these in two subfamilies, the Plagonida and Plectanida,
constituting together the family Plectida (identical with the
"Plagiacanthida" of Hertwig and Bütschli). But at present, regarding the
important relations of these Plectida to the other NASSELLARIA, it seems
more convenient to give to them the rank of an independent suborder of
Radiolaria, under the name #Plectoidea#.

The peculiar structure of the central capsule of the #Plectoidea#, first
recognised by Richard Hertwig, allows no doubt of their being true
MONOPYLEA or NASSELLARIA; and also their siliceous, originally triradiate
skeleton indicates the nearest affinity to {900}the other families of this
legion. But a very difficult and as yet unsolved problem is the important
question, in what manner these different groups of NASSELARIA are
phylogenetically connected. Either the #Plectoidea#--as the simplest of
all--are the original common ancestral group of this whole legion (as I
assumed in my Prodromus, 1881), or they are derived from the #Stephoidea#
(by reduction of the sagittal ring), or they have originated independently
from them (if we suppose a polyphyletic origin of the MONOPYLEA. Compare
above, p. 893, &c.). In any case the typical "triradial structure" of the
#Plectoidea#, prevalent also in the other groups of this legion, is a very
important and interesting fact.

The triradial skeleton of the #Plectoidea# exhibits in the two families of
Plagonida and Plectanida a complete homology of development, so that each
genus of the latter may be derived from a corresponding genus of the
former, simply arisen by concrescence or union of the branches of the
radial spines. Therefore the only difference between the two closely allied
families is, that the branches of the radial spines in the Plagonida remain
free, whilst in the Plectanida they produce a loose framework or wickerwork
by union of their meeting ends. We express this complete homology in the
nomenclature of the #Plectoidea#, in each genus of Plagonida retaining the
syllable "Plag-"; in each genus of Plectanida, correspondingly, the
syllable "Plect-."

The number of radial spines composing the skeleton is originally three, and
in all not triradial genera is probably derived from three. For better
survey we may divide each family, according to the different number of
rays, into four different subfamilies: A, with three radial spines
(Triplagida and Triplectida); B, with four radial spines (Tetraplagida and
Tetraplectida); C, with six radial spines (Hexaplagida and Hexaplectida);
and D, with numerous (seven to nine or more) radial spines (Polyplagida and
Polyplectida). The last three subfamilies have arisen probably from the
first triradial subfamily, by a secondary increase in the number of rays.

The important signification of the triradial structure, recurring in the
most different groups of NASSELLARIA, has been already pointed out
sufficiently by myself and by R. Hertwig. But the triradial #Plectoidea#
offer also another interesting relation of this characteristic structure,
some simple forms of this order appearing nearly identical with the
isolated triradial spicula of certain #Beloidea# (Thalassosphærida and
Sphærozoida). Even some more complex quadriradial and sexradial forms of
the latter reappear in exactly the same shape also in the former. This
identity may be perhaps an important indication of true affinity (compare
below).

The simplest and probably the most original kind of triradial structure is
exhibited by the genera _Triplagia_ and _Triplecta_ (Pl. 91, figs. 2, 7).
Here three equal radial spines lie in one horizontal plane and are united
in a common central point at equal angles, so that three lines connecting
their distal ends form a regular equilateral triangle. Simple triradial
spicula of the same regular form are also found in many {901}#Beloidea#
(_Lampoxanthium_, _Sphærozoum_, &c., Pls. 2 and 4).  The central capsule of
these simplest #Plectoidea# (with vertical main axis) rests perpendicularly
on the horizontal triangle, formed by the triradial skeleton; the porochora
of the former (or the "area porosa") rests upon the central point of the
latter.

Another kind of triradial structure characterises the genera _Plagiacantha_
and _Plectophora_.  The three radial spines united in the central point lie
here not in one plane, but diverge in different planes, so that they
correspond to the three lateral edges of a three-sided pyramid.  Commonly
the three spines are of equal size, and also the angles between them equal,
so that the pyramid is regular, sometimes very flat, at other times more
elevated.  Spicula of exactly the same form are also found in some
#Beloidea#.  Probably the three divergent spines are homologous to the
three basal feet of numerous #Spyroidea# and #Cyrtoidea#.  The central
capsule, according to Hertwig, is placed in the apical part of the pyramid,
the axes of both being identical, and the porochora resting in the apex
itself. This fact seems to contradict the above-mentioned affinity; but
since in _Triplecta_ and _Triplagia_ the three spines lie horizontally,
they may have changed this original position in different direction, in
_Plagiacantha_ and _Plectophora_ becoming divergent upwards, whereas in
_Plagoniscus_ and _Plectaniscus_ (as in the #Spyroidea# and #Cyrtoidea#)
directed downwards.

The triradial structure, common to the Triplagida and Triplectida, is
replaced by the quadriradial structure in the Tetraplagida and
Tetraplectida. Probably the latter have been derived from the former by
development of a fourth spine, and then this latter would correspond to the
"apical horn" of the other NASSELLARIA. But possibly also both structures
have originated independently from one another. We may distinguish not less
than four different kinds of the quadriradial structure. In the first case
all four spines are equal, and diverge from a common central point at equal
angles in different directions, corresponding to the four axes of a regular
tetrahedron (_Tetraplagia_ and _Tetraplecta_, Pl. 91, figs. 3, 8).

In the second case all four spines are also equal, but they are not united
in a common central point, but opposite in pairs on the two poles of a
common central rod (_Plagonidium_). Therefore the skeleton possesses here
the same form as in the "geminate-biradiate" spicula of many #Beloidea#
(_e.g._, _Thalassoxanthium bifurcum_ and _Sphærozoum furcatum_). The
development of the short horizontal middle rod, connecting the two
divergent pairs of spines, is here probably effected by the porochora of
the central capsule resting upon it.

Whilst in these two cases of quadriradial structure all four spines are
equal, in two other cases they become differentiated in a very remarkable
manner. One spine is vertically directed upwards, in shape and size
different from the three others, which are directed downwards; the former
corresponding probably to the "apical horn," the latter to the three "basal
feet," which are found in the great majority of the #Spyroidea# {902}and
#Cyrtoidea#. Therefore we encounter here for the first time that
characteristic "cortinar structure" which is complete in _Cortina_ and
_Cortiniscus_ (Pl. 92, figs. 11-13, 21), and which may be regarded as the
strongest argument for a close relationship, or even for a common
monophyletic origin of all NASSELLARIA.

The four spines, which we regard therefore as "cortinar spines," exhibit a
twofold kind of central junction. In the simpler case they are united in a
common central point, on which rests the porochora of the central capsule
(_Plagoniscus_ and _Plectaniscus_, Pl. 91, figs. 4, 9). These forms are
nearer to _Cortina_, and may be derived immediately from _Tetraplagia_ and
_Tetraplecta_ by differentiation of the four equal spines. In the other
case the four cortinar spines are separated in pairs, diverging from the
two poles of a short horizontal common "central rod" (_Plagiocarpa_ and
_Periplecta_, Pl. 91, figs. 5, 10). These forms may be compared with the
spicula of some #Beloidea# and derived from _Plagonidium_; but their basal
central rod may be compared again with the basal part of the sagittal ring
of _Cortina_, and this comparison becomes very important in those forms
like _Plagiocarpa procortina_ (Pl. 91, fig. 5). Here the four spines
approach very nearly to those of _Cortina_; the two ventral spines (or
pectoral feet) on the anterior pole of of the middle rod are equal, but
very different from the two dorsal spines, arising from the posterior pole;
the lower odd spine of the latter corresponds to the "caudal foot," the
upper spine to the "apical horn" of _Cortina_ and of the #Cyrtellaria#. The
vertical plane, determined by these two dorsal spines, is the sagittal
plane, and two opposite curved branches which lie in this plane (an upper
arising from the basal part of the apical spine and a lower arising from
the anterior pole of the middle rod) may be regarded as ventral parts of an
incomplete sagittal ring. This interesting form and some other similar
Tetraplagida may be regarded either as beginning #Stephoidea# (_Cortina_,
with incomplete sagittal ring) or as retrograde #Stephoidea# (_Cortina_,
with partly reduced sagittal ring). In every case they seem to indicate the
near relationship between the #Stephoidea# and #Plectoidea#.

Another argument for this close relationship may be found in the position
of the central capsule in the interesting genus _Plagiocarpa_ (Pl. 91, fig.
5). Its basal part (with the porochora) rests upon the common central rod,
its ventral face upon the ventral prolongation of the latter, its dorsal
face upon the apical horn; its axis lies in the sagittal plane. The three
basal spines (the odd caudal and the paired pectoral feet) diverge from its
basal pole downwards in the same manner as in the Cortina, the Zygospyrida
and the Monocyrtida.

Less important than those quadriradial Tetraplagida and Tetraplectida, are
the sexradial #Plectoidea#, the Hexaplagida and Hexaplectida. These may be
derived immediately from the triradial #Plectoidea# by prolongation of the
three primary original spines (of _Plagiacantha_) over the common central
point. Here also two {903}different kinds of central junction are found. In
the simpler case all six radial spines arise from a common central point
(_Hexaplagia_ and _Hexaplecta_). In the other case the six radial spines
arise from the two poles of a short horizontal common central rod, opposed
in two groups, each of three spines (_Plagonium_ and _Plectanium_, Pl. 91,
figs. 6, 11).  In this latter case the single corresponding spines of the
two opposite groups are usually parallel, and exhibit therefore exactly the
same characteristic "germinate-triradiate" form which is found in many
#Beloidea# (_e.g._, in the common _Sphærozoum punctatum_ and the similar
_Lampoxanthium punctatum_).

The fourth and last group of this suborder contains the multiradiate
#Plectoidea#, the Polyplagida and Polyplectida. Here the number of radial
spines, diverging from the common centre, exceeds six, and is commonly
seven to nine, at other times ten to twelve or more (_Polyplagia_ and
_Polyplecta_, Pl. 91, fig. 12). When these two genera are better known from
further accurate observations, they may probably be divided into several
different genera (as already proposed in my Prodromus, 1881), since not
only the number, but also the central junction and the arrangement of the
numerous radial spines in the few observed species seems to be very
different. In some seven-radiate species (_e.g._, _Polyplecta heptacantha_)
four larger spines seem to be true "cortinar spines," the three smaller
secondary productions of the former. In the nine-radiate species the nine
spines seem to be sometimes basal branches of three primary spines, at
other times six secondary intercalated between the three primary (like
_Enneaphormis_, Pl. 57, fig. 9). In those multiradial #Plectoidea#, in
which the number of spines amounts to ten or twelve or more, the laws of
disposition are not yet recognised.

Comparing these different productions of the skeleton in the numerous
#Plectoidea#, we find expressed two remarkable and very different
affinities. On the one hand many #Plectoidea# exhibit exactly the same
peculiar forms, which are only found besides in the #Beloidea# (as many
species of _Triplagia_, _Plagiacantha_, _Tetraplagia_, _Plagonidium_,
_Hexaplagia_, and _Plagonium_). On the other hand many #Plectoidea# bear
the same characteristic composition of the skeleton (or the "cortinar
structure") which is found in the Cortinida among the #Stephoidea#, and in
numerous #Spyroidea# and #Cyrtoidea#, which all agree in the possession of
three divergent basal feet and a vertical apical horn. A most important
argument for the close affinity of all these "cortinar NASSELLARIA" seems
to be given by the fact that the sagittal ring, which in _Cortina_ is
combined with the quadriradial structure, exhibits in the #Cyrtellaria# the
most different stages of development; in one group it is complete, in the
second incomplete, and in the third it has completely disappeared.

The form of the radial spines composing the skeleton is usually three-sided
prismatic, gradually tapering from the thicker central base towards the
distal apex; sometimes they are slender pyramidal. More rarely the spines
are cylindrical or slender conical. In the majority of species the spines
are straight, in the minority more or {904}less curved. In very few species
only are they quite simple, without branches. They are nearly always more
or less branched, in many larger species very richly ramified. The modes of
ramification are rather variable. In the majority of #Plectoidea# the
spines are rather regularly verticillate, bearing an increasing number of
verticils, each of which is composed of three divergent branches. These
arise from the three edges of the spine, and all the branches of one edge
are usually parallel, either perpendicular to the spine, or directed at an
acute angle towards its apex. When the verticils are numerous (five to ten
or more), their size commonly tapers gradually towards the apex. Pinnate
spines occur more rarely than verticillate ones; in this case the two
paired lateral edges only of the prismatic spine bear opposite or alternate
branches, whilst the odd middle edge bears no ramules. In some species the
spines are singly or doubly forked. In many species (mainly those with
cylindrical spines) the ramification of the spines is more or less
irregular.

Whilst in all Plagonida the branches of the spine remain perfectly free, in
all Plectanida, again, the meeting ends of the branches become united and
grow together, and by this concrescence a loose network arises, like
wickerwork, which partly encloses the central capsule and the central parts
of the spines, on which it rests. The meshes of this loose wickerwork are
large, either quite irregular, of very different size and form, or more or
less regular, with a certain form and arrangement of the meshes, effected
by the peculiar kind of ramification. Commonly the siliceous threads of the
arachnoidal wickerwork are very thin, often extremely delicate,
representing "pseudopodia metamorphosed into silex." Sometimes the
wickerwork is spongy. Its surface is constantly rough and bristly, with
free ends of the spine-branches, never covered with a regular
lattice-plate, as in the #Cyrtellaria# (#Spyroidea#, #Botryodea#, and
#Cyrtoidea#).

The entire form of the central wickerwork is in the minority of Plectanida
quite irregular and indefinite; in the majority, however, a certain more or
less regular entire form is recognisable, effected by a certain, more or
less regular origin and mode of the connection of the meeting branches. So
in some species of _Triplecta_ (Pl. 91, fig. 7) the network represents a
triangular plate, of _Plectophora_ and _Plectaniscus_ a three-sided
pyramid, of _Tetraplecta_ (Pl. 91, fig. 3) a tetrahedron, and in many other
species a polyhedron of more or less regular form. Some species of
Plectanida become very similar to certain species of #Stephoidea#,
#Spyroidea#, and #Cyrtoidea#; so _Plectaniscus_ and _Periplecta_ approach
to _Cortina_ and _Cortiniscus_, _Pteroscenium_ and _Clathrocorys_, &c.
(compare Pls. 92, 93, 53, 64, &c.). They may represent a true phylogenetic
connection between both groups. But in these cases also the distinction is
determined by the fact that the true #Plectoidea# never possess a complete
sagittal ring (like the #Stephoidea#) nor a regular lattice-shell (like the
#Spyroidea#, #Botryodea#, and #Cyrtoidea#).

{905}_The Central Capsule_ of the #Plectoidea# constantly exhibits the
peculiar characters of the MONOPYLEA or NASSELLARIA. It is commonly ovate,
more rarely ellipsoidal or even spherical, sometimes conical or
lentelliptical. The lower or basal pole of its vertical main axis
constantly exhibits the characteristic "porochora" (or the area porosa) of
the MONOPYLEA, and upon this rests the peculiar "podoconus" (or the
pseudopodial-cone) of this legion. On this porochora the central capsule is
in immediate connection with the central point of the skeleton, or the
horizontal common central rod, from which the radial spines arise. The
endoplasm, or the protoplasm of the central capsule (besides the
podoconus), contains commonly one large alveole or several small vacuoles,
and often pigment-granules. The nucleus is large, spherical or ovate, and
exhibits the same character as in all the other MONOPYLEA; it encloses
usually a single nucleolus.

The position of the central capsule and its topographical relation to the
skeleton offers in the different #Plectoidea# some important and as yet
unsolved problems, which can be answered only by fresh and accurate
observations on living specimens. In _Triplagia_ and _Triplecta_, where the
triangular skeleton lies in a horizontal plane, the vertical main axis of
the central capsule is perpendicular to the central point of that
supporting triangle. In _Plagiacantha_ and _Plectophora_, where the three
radial spines correspond to the edges of a flat pyramid, the capsule is
enclosed in the pyramidal space of the latter, its basal pole touching the
apex; therefore in the normal position of the body the three divergent rays
are directed upwards. In _Tetraplagia_ and _Tetraplecta_ probably the same
position is retained, and therefore the fourth free spine, here developed,
is probably directed vertically downwards. In _Plagoniscus_ and
_Plectaniscus_, however, and moreover, in the closely allied _Plagiocarpa_
and the corresponding _Periplecta_ (Pl. 91, figs. 5, 10) the position of
the central capsule, relative to the skeleton, seems to be inverse, and to
agree with that of the #Stephoidea# (_Cortina_, _Cortiniscus_, &c.) and the
#Cyrtoidea# (_Pteroscenium_, _Clathrocorys_, &c.); the three divergent
spines are here directed downwards (as basal feet), whilst the opposite
fourth spine is vertically directed upwards (as an apical horn); the
capsule rests here upon the tripod, which lies below it, and is inclined
with its dorsal face to the apical spine. In the majority of the other
#Plectoidea# the position of the central capsule and its relation to the
skeleton are not yet sufficiently observed, and require further accurate
researches. Its position seems to be very different in the several genera.
The capsule is never perforated by parts of the skeleton; this latter is
constantly extra-capsular.

The physiological value of the skeleton, with regard to the central
capsule, is different in the Plagonida and Plectanida; in the former it
supports, in the latter it encloses the capsule like a shell. In the
Nassellida, where no skeleton is developed, the central capsule is quite
free and naked, enveloped only by the calymma.

{906}The calymma or the extracapsular jelly-veil in all #Plectoidea# is
voluminous, and encloses not only the central capsule completely, but also
the skeleton wholly or partially. Its form is of the greatest value for the
development and configuration of the skeleton. Sometimes the calymma is
alveolate and foamy, as in _Nassella_ and the common _Thalassicolla_. In
several other #Plectoidea# the calymma seems to include numerous small
vacuoles, sometimes also pigment-granules. Xanthellæ are commonly scattered
in it in great numbers. The pseudopodia, arising in a large bunch from the
porochora of the capsule, and running along the branches of the radial
spines, seem to be always numerous, richly branched, and with a strong
tendency to form anastomoses. The peculiar form of their network is often
exactly preserved in the conformation of the skeleton, produced by them.
The peculiarities of this network require further accurate observations, as
does the whole organisation of the #Plectoidea#.

_Synopsis of the Families of_ #Plectoidea#.

   I. Skeleton (originally tripodal) composed of radial
      spines united in a common centre and supporting the
      central capsule, without wicker-work,                  1. PLAGONIDA.

  II. Skeleton (originally tripodal) wattled, with irregular
      wicker-work, composed of the united branches of radial
      spines and enveloping the central capsule,             2. PLECTANIDA.



Family XLVI. #PLAGONIDA#, Haeckel.

  _Plagonida_, Haeckel, 1881, Prodromus, p. 423.
  _Plagiacanthida_ (_sensu strictiori_), Richard Hertwig, 1879, Organismus
      d. Radiol., p. 72.

_Definition._--#Plectoidea# with a spiny skeleton, composed of radial
spines, which arise from a common central point or central rod, and support
the free central capsule.

The family #Plagonida# comprises those NASSELLARIA in which the skeleton is
only composed of united radial spines, arising from a common centre,
without any connection of meeting branches of the spines; the rudimentary
skeleton exhibits therefore neither a loose wickerwork (as in the closely
allied Plectanida), nor a ring (as in the #Stephoidea#), nor a complete
lattice-shell (as in the #Cyrtellaria#, the #Spyroidea#, #Botryodea#, and
#Cyrtoidea#). The central capsule, which possesses all the characters of
the MONOPYLEA, is therefore free, not enclosed, and only on one side
supported or partly protected by the radial spines or their branches.

Two species only of Plagonida have been hitherto known. The first form
described is the _Plagiacantha arachnoides_, discovered thirty years ago
(1855) by Claparède on the western shore of Norway. Another species of the
same genus, from the Mediterranean, was very accurately described by
Richard Hertwig in 1879 in his Organismus der {907}Radiolarien
(_Plagiacantha abietina_). Upon these two species the latter founded his
family Plagiacanthida, a term which was afterwards employed by Bütschli and
others, for the whole group of #Plectoidea#. Many new forms are contained
in the collection of the Challenger, so that we may describe here nine
genera and thirty-four species.

The family Plagonida may be divided into four different subfamilies,
according to the numbers of the radial spines which compose the skeleton:
Triplagida with three, Tetraplagida with four, Hexaplagida with six, and
Polyplagida with numerous (seven to nine or more) radial spines. These are
united commonly in one common central point, upon which rests the basal
pole of the central capsule, with the porochora. More rarely (in the genera
_Plagonidium_, _Plagiocarpa_, and _Plagonium_) the spines arise in two
opposite groups (each with two or three spines) from the two poles of a
common central rod; in this case the basal pole of the central capsule with
the porochora rests upon the horizontal common rod, which corresponds
probably to the basal part of the sagittal ring of the #Stephoidea# and
#Cyrtellaria#.

The different forms which the skeleton of the Plagonida assumes in the
different genera of this family, and the important relations which these
exhibit on the one hand to the spicula of the #Beloidea#, and on the other
hand to the shell of some #Stephoidea# (_Cortina_, _Cortiniscus_, &c.) and
#Cyrtoidea# (_Pteroscenium_, _Clathrocorys_, &c.), have been already
pointed out in the preceding description of the suborder #Plectoidea#.
There it is also demonstrated, that all these different forms may be
derived from the simplest triradial forms, _Triplagia_ and _Plagiacantha_
(compare above, pp. 900-904).

Whilst the genera of the Plagonida are characterised by the number of the
radial spines and the peculiar mode of junction in a common central point
or at the two poles of a common central rod, the different species of this
family may be defined by the peculiar form of the spines and their
branches. These morphological characters have also been already described
above. We repeat here only that the radial spines in the majority of
species are three-sided prismatic and verticillate, each verticil commonly
with three branches. The distal ends of these branches remain constantly
free, and are never united, as is always the case in the following family.

_The Central Capsule_ of the Plagonida exhibits the general characters of
all MONOPYLEA (compare above, p. 890). It is commonly ovate or ellipsoidal,
with vertical main axis; on the lower pole of the latter is the porochora
(or the "area porosa," from which all pseudopodia radiate). This is in
immediate connection with the central point or central rod of the skeleton,
in which its radial spines are united. The topographical relation of the
supporting skeleton to the central capsule seems to exhibit in the
different genera of the Plagonida remarkable differences, as already
demonstrated above (p. 905).

{908}_Synopsis of the Genera of Plagonida._

  -------------------------------------------------------------------------
  I. Subfamily Triplagida. Three radial spines.
  -------------------------------------------------------------------------
  Three spines lying in one horizontal plane,          384. _Triplagia_.

  Three spines corresponding to the edges of a flat
    pyramid,                                           385. _Plagiacantha_.
  -------------------------------------------------------------------------
  II. Subfamily Tetraplagida. Four radial spines.
  -------------------------------------------------------------------------
                              {All four spines equal,  386. _Tetraplagia_.
  Four spines arising from    {
    one common central point. {One apical spine
                              {  opposed to three
                              {  basal spines,         387. _Plagoniscus_.

                              {All four spines equal,  388. _Plagonidium_.
  Four spines arising in two  {
    pairs from the poles of a {One apical spine
    common central rod.       {  opposed to three
                              {  basal spines,         389. _Plagiocarpa_.
  -----------------------------------------------------------------
  III. Subfamily Hexaplagida. Six radial spines.
  -----------------------------------------------------------------
  Six spines arising from one common central point,    390. _Hexaplagia_.

  Six spines arising in two opposite groups from the
    poles of a common central rod,                     391. _Plagonium_.
  -----------------------------------------------------------------
  IV. Subfamily Polyplagida. Numerous radial spines.
  -----------------------------------------------------------------
  Numerous (seven to nine or more) radial spines
    arising from a common centre (either a central
    point or a branched rod),                          392. _Polyplagia_.



Subfamily 1. TRIPLAGIDA, Haeckel, 1881, Prodromus, p. 423.

_Definition._--#Plagonida# with three radial spines.



Genus 384. _Triplagia_,[3] Haeckel, 1881, Prodromus, p. 423.

_Definition._--#Plagonida# with three radial spines, arising from one
common central point and lying in one horizontal plane.

The genus _Triplagia_ and the following closely allied _Plagiacantha_ may
be regarded as the simplest and most primitive forms of the #Plectoidea#,
perhaps as the common ancestral stock of this suborder. The skeleton is
composed of three simple or branched radial spines, arising from one common
central point. These three spines in _Triplagia_ lie in one and the same
plane, whilst in _Plagiacantha_ they lie in different planes. Therefore the
former exhibits the simplest type of the triradial structure, common to the
majority of NASSELLARIA.


{909}1. _Triplagia primordialis,_ n. sp. (Pl. 91, fig. 2).

Spines straight, of equal size and similar form, equidistant, three-sided
prismatic, each with two pairs of opposite lateral branches, which are
correspondingly parallel to the two other spines; the proximal branches
twice as long as the distal branches.

_Dimensions._--Length of each spine 0.2, of the basal branches 0.07.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Triplagia triradialis,_ n. sp.

Spines straight, of equal size and similar form, equidistant, three-sided
prismatic, regularly pinnate, with six pairs of opposite pinnulæ, tapering
gradually towards the distal ends; the basal pinnulæ are again branched,
with straight ramules.

_Dimensions._--Length of each spine 0.27, of the basal branches 0.08.

_Habitat._--North Pacific, Station 256, surface.


3. _Triplagia horizontalis,_ n. sp.

Spines curved, cylindrical, irregularly branched, with three primary and
nine to twelve secondary branches, which are also slightly curved. The
angles between the bases of the three spines are equal, but the size and
form of the branches different.

_Dimensions._--Length of the three spines 0.15 to 0.25, of the basal
branches 0.05 to 0.08.

_Habitat._--West Tropical Pacific, Station 226, depth 4475 fathoms.



Genus 385. _Plagiacantha_,[4] Claparède, 1856, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, November 13.

_Definition._--#Plagonida# with three radial spines, arising from one
common central point and corresponding to the edges of a three-sided
pyramid.

The genus _Plagiacantha_ agrees with the preceding _Triplagia_ in the
simple structure of the triradial skeleton, composed of three diverging
radial spines, which are united in a common centre at the oral pole of the
central capsule. But whilst the three radial rods of _Triplagia_ lie in one
horizontal plane, here they lie in different planes and correspond to the
three edges of a flat pyramid. _Plagiacantha arachnoides_, described in
1856 by Claparède, was the earliest known form of all #Plectoidea#.


{910}1. _Plagiacantha arachnoides_, Claparède.

  _Plagiacantha arachnoides_, Claparède, 1856, Monatsber. d. k. preuss.
  Akad. d. Wiss. Berlin, November 13.

  _Plagiacantha arachnoides_, Claparède, 1858, Études sur les Infusoires et
  les Rhizopodes, p. 462 (pl. xxii. fig. 8).

  _Acanthometra arachnoides_, Claparède, 1855, Monatsber. d. k. preuss.
  Akad. d. Wiss. Berlin, p. 675.

Spines straight, cylindrical, divided into three divergent straight
branches of equal size; each branch two to three times as long as the
simple thicker basal part.

_Dimensions._--Length of the spines 0.12 to 0.2 of the branches 0.08 to
0.14.

_Habitat._--North Atlantic, coast of Norway, Claparède, surface.


2. _Plagiacantha furcata_, n. sp.

Spines straight, cylindrical, divided into two divergent straight branches
of equal size, of about the same length as the simple basal part. The
spines and their branches are smooth.

_Dimensions._--Length of the spines 0.24, of their fork-branches 0.12.

_Habitat._--North Pacific, Station 254, surface.


3. _Plagiacantha dodecantha_, n. sp.

Spines straight, three-sided prismatic, in the middle with one verticil
composed of three divergent straight branches of equal size, of about the
same length as the simple basal part. The edges of the spines and their
branches are thorny.

_Dimensions._--Length of the spines 0.24, of the branches 0.1.

_Habitat._--Central Pacific, Station 274, surface.


4. _Plagiacantha abietina_, Richard Hertwig.

  _Plagiacantha abietina_, Richard Hertwig, 1879, Organismus d. Radiol., p.
  72, Taf. vii. figs. 6-6_b_.

Spines straight, three-sided prismatic, with three verticils of three
divergent straight lateral branches, decreasing in size towards the distal
end; the branches of the first verticil about twice as long as those of the
second, and four times as long as those of the third verticil.  All nine
branches of each spine simple, straight, three-sided pyramidal.

_Dimensions._--Length of the spines 0.2 to 0.3, of the basal branches 0.06
to 0.08.

_Habitat._--Mediterranean, Messina (R. Hertwig), surface.


5. _Plagiacantha verticillata_, n. sp.

Spines curved, three-sided prismatic, with six to nine verticils of three
divergent branches, decreasing in size towards the distal end; the branches
of the first verticil about twice as long as those of the fourth verticil.
All branches simple, slightly curved, bristle-shaped.

_Dimensions._--Length of the spines 0.27, of the basal branches 0.12.

_Habitat._--South Pacific, Station 296, surface.


{911}6. _Plagiacantha elatine_, n. sp.

Spines straight, three-sided prismatic, with prominent wing-like edges and
ten to twelve verticils of three divergent branches, decreasing in size
towards the distal end; the branches of the three or four basal verticils
are again ramified and much larger than the simple branches of the distal
verticils.

_Dimensions._--Length of the spines 0.36, of the basal branches 0.14.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Subfamily 2. TETRAPLAGIDA, Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plagonida# with four radial spines.



Genus 386. _Tetraplagia_,[5] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plagonida# with four equal radial spines, arising from one
common central point, and corresponding to the four axes of a tetrahedron.

The genus _Tetraplagia_ is one of the most important #Plectoidea#, and
possibly the common ancestral form of many NASSELLARIA (compare above, p.
901). The skeleton is composed of four radial rods, diverging from one
common centre in different directions, and corresponding to the four axes,
which extend from the central point of a tetrahedron to the central points
of its four faces. The whole skeleton of _Tetraplagia_ exhibits therefore
the same form, which is observed in the single quadriradiate spicula of
some #Beloidea# (in some species of _Lampoxanthium_, _Sphærozoum_, &c.).


1. _Tetraplagia geometrica_, n. sp.

Spines straight, cylindrical, perfectly equal, corresponding in regular
disposition exactly to the four geometrical axes of a regular tetrahedron;
in the middle arise from each spine two opposite equal lateral branches of
half the length of the spine.

_Dimensions._--Length of the spines 0.12, of the branches 0.06.

_Habitat._--Central Pacific, Station 266, surface.


2. _Tetraplagia phænaxonia_, n. sp. (Pl. 91, fig. 3).

Spines straight or slightly curved, three-sided prismatic, with irregular
short branches arising from the three edges; the branches are thorny,
tapering towards the apex.

_Dimensions._--Length of the spines 0.15, of the basal branches 0.03.

_Habitat._--Tropical Atlantic, Station 332, surface.


{912}3. _Tetraplagia abietina_, Haeckel.

  _Plagiacantha abietina_, var. _quadrispina_, Richard Hertwig, 1879,
  Organismus d. Radiol., p. 73.

Spines straight, three-sided prismatic, verticillate, with six to eight
verticils of three simple straight branches; the branches of each edge are
parallel, tapering towards the distal end. R. Hertwig regards this species
only as a four-spined variety of his three-spined _Plagiacantha abietina_;
but a specimen, observed by me in Corfu, exhibited all the characters of
_Tetraplagia_.

_Dimensions._--Length of the spines 0.2, of the basal branches 0.07.

_Habitat._--Mediterranean (Messina, Corfu), surface.



Genus 387. _Plagoniscus_,[6] n. gen.

_Definition._--#Plagonida# with four unequal radial spines, arising from
one common central point; one vertical or apical spine opposed to three
divergent or basal spines.

The genus _Plagoniscus_ agrees with the preceding _Tetraplagia_ (its
probable ancestral form) in the possession of four radial spines, diverging
from one common central point. But whilst in this latter all four spines
are equal, corresponding exactly to the four axes of a tetrahedron, here in
_Plagiocarpa_ an important difference exists between one vertical or apical
spine and three other divergent basal spines; these latter corresponding
probably to the three "feet," the former to the single "apical horn" of the
majority of NASSELLARIA. Perhaps we find here one of the oldest and
simplest types of their "triradial or cortinar structure" (compare above,
p. 902).


1. _Plagoniscus tripodiscus_, n. sp. (Pl. 91, fig. 4).

Spines three-sided prismatic, thorny. Apical spine nearly straight,
verticillate, with four to five verticils of three thorny branches,
tapering towards the apex. Three basal spines somewhat shorter, curved,
with three thorny edges.

_Dimensions._--Length of the apical spine 0.2, of the basal spines 0.15.

_Habitat._--Central Pacific, Station 263, surface.


2. _Plagoniscus euscenium_, n. sp.

Spines three-sided prismatic, thorny, with dentate edges, and three to six
verticils of three short branches. Apical spine straight, with six
verticils, nearly twice as long as the three curved basal spines, each of
which bears three verticils; the basal verticils larger and ramified.
Resembles somewhat Euscenium eucolpium, Pl. 53, fig. 12, but has no
latticed shell.

_Dimensions._--Length of the apical spine 0.3, of the basal spines 0.16.

_Habitat._--North Pacific, Station 247, surface,


{913}3. _Plagoniscus cortinaris_, n. sp.

Spines three-sided prismatic, straight, verticillate. Apical spine with
twelve verticils, one and a half times as long as the three basal spines,
each of which bears eight verticils of three branches. The branches are
also prismatic, straight, on each edge parallel, tapering towards the apex,
in the three basal spines forked, in the apical spine more branched.
Similar to the cortinar skeleton of _Clathrocorys_ (Pl. 64, figs. 8-10).

_Dimensions._--Length of the apical spine 0.24, of the basal spines 0.16.

_Habitat._--South Atlantic, Station 338, surface.


4. _Plagoniscus nassellaris_, n. sp.

Spines cylindrical, curved, irregularly branched. Apical spine half as long
as, and less branched than the three basal spines, which are sigmoidal,
nearly horizontally expanded in the proximal half, descending in the distal
half.

_Dimensions._--Length of the apical spine 0.1, of the three basal spines
0.18.

_Habitat._--West Tropical Pacific, Station 224, surface.



Genus 388. _Plagonidium_,[7] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plagonida# with four equal radial spines, arising in pairs
from the two poles of a common central rod.

The genus _Plagonidium_, and the following _Plagiocarpa_ possess four
radial spines, like the two preceding genera. But whilst the four rods in
these latter arise from a common centre, here they arise in two pairs from
the two poles of a common middle rod; they have therefore exactly the same
form which we find in the single spicula of some #Beloidea# (e.g.,
_Thalassoxanthium furcatum_, _Sphærozoum furcatum_, &c.). Probably the
middle rod is horizontal and serves as supporting base for the central
capsule, whilst two opposite spines are directed upwards, two other
downwards.


1. _Plagonidium bigeminum_, n. sp.

Spines straight, three-sided prismatic, four to six times as long as the
common central rod, pinnate, with four to five pairs of opposite pinnulæ,
the distal of which are simple, the proximal again branched.

_Dimensions._--Length of the spines 0.16, of the middle rod 0.032.

_Habitat._--Indian Ocean, Sunda Strait (Rabbe), surface.


{914}2. _Plagonidium quadrigeminum_, n. sp.

Spines cylindrical, curved, eight to ten times as long as the common
central rod, in the distal half forked; the fork-branches curved, somewhat
longer than the basal part.

_Dimensions._--Length of the spines 0.18, of the middle rod 0.02.

_Habitat._--Antarctic Ocean, Kerguelen Island, Station 159, surface.



Genus 389. _Plagiocarpa_,[8] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plagonida# with four unequal radial spines, arising in
pairs from the two poles of a common central rod; one ascending apical
spine opposed to three descending basal spines.

The genus _Plagiocarpa_ agrees with the preceding _Plagonidium_ in the
possession of a common horizontal middle rod, the two poles of which bear
two pairs of divergent spines; but whilst in the preceding all four spines
are equal, here they are differentiated in the same manner as in
_Plagoniscus_, which differs only in the absence of the middle rod. The two
observed and closely allied species of this genus are of peculiar interest,
since they belong possibly to the common ancestral forms of the
NASSELLARIA; the basal middle rod corresponds perhaps to the basal part of
a sagittal ring, the apical spine to its dorsal part, the three other
spines to the basal feet (compare above, p. 902).


1. _Plagiocarpa procortina_, n. sp. (Pl. 91, fig. 5).

Spines cylindrical, curved, thorny, three to four times as long as the
common middle rod. Apical spine and the meeting caudal spine (or the
posterior basal spine) somewhat longer and with more numerous thorns than
the two paired pectoral (or anterior) spines. From the common base of the
latter arises an anterior prolongation of the horizontal middle rod, which
in the sagittal plane is curved upwards and corresponds to the sternal foot
of many #Cyrtellaria#. An ascending branch of this spine is opposed to a
descending branch of the apical spine, both together forming an incomplete
sagittal ring.

_Dimensions._--Length of the two larger spines 0.15, of the two smaller
0.12.

_Habitat._--Mediterranean (Portofino near Genoa), surface.


2. _Plagiocarpa procyrtella_, n. sp.

Spines of form and arrangement similar to those of the preceding species,
but longer and more branched, six to eight times as long as the shorter
common middle rod. The two characteristic {915}opposed branches (the
ascending branch of the basal rod and the descending branch of the apical
spine), which in the preceding species nearly compose a sagittal ring, are
here absent.

_Dimensions._--Length of the two larger 0.27, of the two smaller 0.21.

_Habitat._--North Atlantic, Iceland (Steenstrup), surface.



Subfamily 3. HEXAPLAGIDA, Haeckel.

_Definition._--#Plagonida# with six radial spines.



Genus 390. _Hexaplagia_,[9] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plagonida# with six radial spines, arising from one common
central point.

The genus _Hexaplagia_ differs from the preceding genera of Plagonida in
the possession of six radial spines, diverging from one common central
point. Commonly, these six spines seem to lie opposite in pairs in three
different meridian planes, and in this case _Hexaplagia_ may be regarded as
a _Plagiacantha_, the three radial spines of which are prolonged over the
basal pole of the central capsule. But in other species the six spines seem
to lie in different planes. Further observations are required.


1. _Hexaplagia arctica_, n. sp.

Spines opposite in pairs in three diameters, crossed in the common centre,
straight, three-sided prismatic, with dentate edges. The three pairs are
equal, but the upper spine of each pair only half as long as the lower
spine.

_Dimensions._--Length of the upper spine 0.13, of the lower 0.27.

_Habitat._--Arctic Ocean (Greenland), in the stomach of a Medusa (Olrik).


2. _Hexaplagia antarctica_, n. sp.

Spines opposite in pairs in three diameters, crossed in the common centre,
slightly curved, three-sided prismatic, with verticillate branches; the
three pairs are equal, but the lower spine of each pair bears three to four
verticils, each of three branches, and is two to three times as long as the
upper spine, which bears two verticils only.

_Dimensions._--Length of the upper spine 0.12, of the lower 0.3.

_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.


{916}3. _Hexaplagia collaris_, n. sp.

Spines in opposite pairs in three diameters, crossed in the common centre,
straight, cylindrical, pinnate, with three to four pairs of opposite
lateral branches or regular pinnulæ. All six spines are equidistant, of
equal size and similar form, and lie with their branches nearly in one
horizontal plane. Therefore they are similar to the six radial rods in the
collar septum of many #Spyroidea# and #Cyrtoidea# (_e.g._, _Calpophæna_,
Pl. 53, fig. 18).

_Dimensions._--Length of all six spines 0.18, of their basal pinnulæ 0.04.

_Habitat._--East of New Zealand, Station 169, surface.


4. _Hexaplagia australis_, n. sp.

Spines unequal, at unequal intervals, not opposite in pairs, cylindrical,
irregularly branched and curved. In this species a definite arrangement of
the six different spines could not be detected.

_Dimensions._--Length of the spines 0.2 to 0.3, of their largest branches
0.1.

_Habitat._--South of Australia, Station 160, surface.



Genus 391. _Plagonium_,[10] Haeckel, 1881, Prodromus, p. 423.

_Definition._--#Plagonida# with six radial spines, arising in two opposite
divergent groups from the two poles of a common central rod.

The genus _Plagonium_ differs from the preceding closely allied
_Hexaplagia_ in the remarkable peculiarity, that the six radial spines do
not arise from one common central point, but from the two poles of a common
horizontal middle rod; three divergent spines on each pole. The skeleton of
_Plagonium_ exhibits therefore the same remarkable form which is found in
the isolated spicula of numerous #Beloidea# (_e.g._, _Lampoxanthium
punctatum_, _Sphærozoum punctatum_), and bears the same relation to
_Hexaplagia_ that _Plagonidium_ does to _Tetraplagia_.


1. _Plagonium sphærozoum_, n. sp. (Pl. 91, fig. 6).

Spines straight and stout, three-sided prismatic, about twice as long as
the common middle rod, irregularly branched or nearly verticillate, with
short thorny branches. Similar to the single spicula of some species of
_Sphærozoum_ and _Lampoxanthium_.

_Dimensions._--Length of the spines 0.12, of the middle rod 0.06.

_Habitat._--Equatorial Atlantic, Station 347, surface.


{917}2. _Plagonium lampoxanthium_, n. sp.

Spines irregularly curved, slender, cylindrical, six to eight times as long
as the common middle rod, in the proximal half smooth, in the distal half
covered with short thorns. (Similar to an isolated spiculum of
_Lampoxanthium punctatum_ or of _Sphærozoum variabile_, Pl. 4, fig. 5.)

_Dimensions._--Length of the spines 0.18, of the middle rod 0.03.

_Habitat._--North Pacific, Station 240, surface.


3. _Plagonium arborescens_, n. sp.

Spines irregularly curved and branched, slender, cylindrical, thorny,
twelve to sixteen times as long as the middle rod; the branches are large,
arborescent, their ramules again ramified and very thorny.

_Dimensions._--Length of the spines 0.2 to 0.25, of the middle rod 0.02.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.


4. _Plagonium trigeminum_, n. sp.

Spines straight, slender, cylindrical, four to six times as long as the
middle rod, in the basal half smooth, in the distal half arborescent, with
three to four irregular verticils of ramified branches. (Similar to a
single spiculum of _Sphærozoum verticillatum_, Pl. 4, fig. 7.)

_Dimensions._--Length of the spines 0.15 to 0.2, of the middle rod 0.05.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


5. _Plagonium distriactis_, n. sp.

Spines straight and stout, three-sided prismatic, smooth, ten to twelve
times as long as the middle rod; each on the distal end cleft into three
divergent straight branches, which are again trichotomous.

_Dimensions._--Length of the spines 0.15 to 0.18, of the middle rod 0.015.

_Habitat._--South Pacific, Station 288, surface.



Subfamily 4. POLYPLAGIDA, Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plagonida# with numerous (seven to nine or more) radial
spines.



Genus 392. _Polyplagia_,[11] n. gen.

_Definition._--#Plagonida# with numerous (seven to nine or more) radial
spines, arising from a common centre and lying in different planes.

{918}The genus _Polyplagia_ alone represents the small subfamily of
Polyplagida, distinguished from the other Plagonida by the multiplication
of the radial spines, the number of which amounts to seven to nine or more.
This increased number is commonly the result of an intercalation of new
spines between the three or four primary spines; it is sometimes also
effected by stronger development of branches of the latter, which become
independent. The following five species of this genus are very different,
require further investigation, and perhaps represent different genera:--


1. _Polyplagia septenaria_, n. sp.

Seven radial spines, straight, three-sided prismatic, verticillate, of
different sizes; four larger spines correspond to the four axes of a
tetrahedron (running from the centre to the four corners), each with five
to six verticils of three simple slender branches; one of these four main
spines seems to be the apical, the three others the basal spines of
_Plagiocarpa_; in the three meridian planes between the latter and the
former lie the three smaller spines, diverging upwards, each with two to
three verticils. (Similar to _Polyplecta heptacantha_, Pl. 91, fig. 12, but
without connection between the branches.)

_Dimensions._--Length of the four major spines 0.26, of the three minor
0.11.

_Habitat._--Central Pacific, Station 274, surface.


2. _Polyplagia octonaria_, n. sp.

Eight radial spines, straight, three-sided prismatic, of equal size,
arising in two opposite groups from the two poles of a short common middle
rod (as in _Sphærozoum arborescens_, Pl. 4, fig. 8, and in other
#Beloidea#). The four spines of each group are divergent, six to eight
times as long as the middle rod, each spine armed with three to four
verticils of thorny branches.

_Dimensions._--Length of the spines 0.15, of the middle rod 0.022.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.


3. _Polyplagia novenaria_, n. sp.

Nine radial spines of equal size, straight, cylindrical, lying nearly in a
horizontal plane, or forming a very flat pyramid. Near the common central
point every three spines arise from a short common rod, so that the centre
of the skeleton is triradial. Each spine bears towards the apex two
divergent straight lateral branches. This species may have been derived
from _Plagiacantha arachnoides_ by shortening and reduction of the basal
parts of the three original branched primary spines.

_Dimensions._--Length of the nine spines 0.24, of the three basal rods
0.02.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray,
surface.


4. _Polyplagia duodenaria_, n. sp.

Twelve radial spines of equal size, arising from a common central point,
and diverging in different directions. The twelve spines are very large,
opposite in six pairs, cylindrical, longitudinally {919}striped (the
expression of concentric lamellæ), and with spinulate surface, covered with
innumerable small thorns. The basal quarter of each spine is straight and
simple, the second quarter twice forked, and these four fork-branches are
again in the outer half of the spine richly forked or ramified, with
diverging, slightly curved thin branches; each of the twelve spines with
about sixty to eighty terminal branches, the ends of which seem to fall
into a spherical face. The position of this remarkable species in this
family is doubtful.

_Dimensions._--Length of the spines 0.12 to 0.16, of the simple basal part
0.04.

_Habitat._--South Pacific (off Juan Fernandez), Station 299, surface.


5. _Polyplagia viminaria_, n. sp.

Numerous (sixteen to twenty or more) radial spines of about equal size,
arising from a common central point and diverging in different directions,
richly and more or less irregularly branched. The ends of the numerous
small branches seem to fall into a spherical face. The large spines of this
species have the same form and structure as in the preceding, nearly allied
species, but are more numerous and more irregularly branched and disposed.

_Dimensions._--Length of the spines 0.2 to 0.25, of the simple basal part
0.05.

_Habitat._--North Pacific, Station 241, surface.



Family XLVII. #Plectanida#, Haeckel.

  _Plectanida_, Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plectoidea# with a wattled skeleton, composed of the
meeting and united branches of radial spines, which arise from a common
central point or central rod, and protect the partly enclosed central
capsule.

The family #Plectanida# comprises those NASSELLARIA in which the skeleton
is composed of radial spines, arising from a common centre, and of a loose
wickerwork, produced by concrescence of the meeting branches of those
spines. This rudimentary wattled skeleton is either quite irregular or only
slightly regular, but it never assumes the form of a complete
lattice-shell, as in the #Cyrtellaria# (the #Spyroidea#, #Botryodea#, and
#Cyrtoidea#), nor does it exhibit a ring (as in the #Stephoidea#). The
central capsule is partly or wholly protected, and often entirely enclosed
by the wattled skeleton.

Three species only of Plectanida have been hitherto known. The first
described form is _Plectophora arachnoides_, which its discoverer Claparède
observed in a living state in 1855 on the western coast of Norway, and
considered as a mere variety of his _Plagiacantha arachnoides_. Two other
species were afterwards observed in the Mediterranean, _Polyplecta
dumetum_, 1856, by Johannes Müller (united by him with _Acanthodesmia_) and
_Polyplecta polybrocha_ by myself in 1864. Many new forms are found in the
{920}collection of the Challenger, so that we may here distinguish eight
genera and twenty-seven species.

The family Plectanida may be divided into four different subfamilies,
according to the number of the radial spines which compose the skeleton.
Those four subfamilies, as also the genera contained in them, correspond
exactly to the four subfamilies of Plagonida, from which they have
originated: Triplectida with three, Tetraplectida with four, Hexaplectida
with six, and Polyplectida with numerous (seven to nine or more) radial
spines. These spines are usually united (as in the corresponding ancestral
Plagonida) in one common central point, upon which rests the basal pole of
the central capsule, with the porochora. More rarely (in the genera
_Periplecta_ and _Plectanium_) the spines arise in two opposite groups
(each of two or three spines) from the two poles of a common horizontal
central rod, which supports the overlying porochora of the central capsule.

The different genera of Plectanida, which are enumerated in the following
synopsis, correspond so exactly to the different genera of Plagonida
described above, that probably each of the former has arisen from a
corresponding genus of the latter. The only difference between the two is,
that in all Plagonida the branches and ramules of the radial spines end
freely, without growing together, whilst in all Plectanida the meeting ends
of the neighbouring spines grow together and so produce a loose and
irregular wickerwork. Therefore the latter constantly possess meshes, which
are missing in the former. As soon as any form of Plagonida begins to
produce meshes by concrescence of meeting branches of the spines, it passes
over into a corresponding form of Plectanida. The loose wickerwork or
wattlework so produced is sometimes very irregular, at other times more or
less regular; but it never assumes the regular form of a complete
lattice-shell, as in the #Cyrtellaria# (#Spyroidea#, #Botryodea#, and
#Cyrtoidea#). The general differences which this wickerwork exhibits in the
different genera of Plectanida have been already described above (compare
pp. 900-904).

_The Central Capsule_ of the Plectanida agrees perfectly with that of the
ancestral Plagonida, as well in general form and structure as in the
peculiar topographical relation to the radial spines (compare above, p.
905). A slight difference between the two families is effected by the
higher development of the skeleton in the Plectanida. Since the branches of
the radial spines in this family become united and form a loose wickerwork,
the central capsule becomes more or less enclosed by the latter, and more
perfectly protected, than in the Plagonida, where the branches remain free.
In this respect the Plectanida approach more nearly to the #Cyrtoidea# with
which they are connected by such transitional forms as _Plectaniscus_ and
_Periplecta_ on the one hand, _Cladoscenium_ and _Pteroscenium_ on the
other.

{921}_Synopsis of the Genera of Plectanida._

  -------------------------------------------------------------------------
  I. Subfamily Triplectida. Three radial spines.
  -------------------------------------------------------------------------
  Three spines lying in one horizontal plane,          393. _Triplecta_.

  Three spines corresponding to the edges of a flat
    pyramid,                                           394. _Plectophora_.
  -------------------------------------------------------------------------
  II.  Subfamily Tetraplectida Four radial spines.
  -------------------------------------------------------------------------
                           { All four spines equal,    395. _Tetraplecta_.
  Four spines arising from {
    one common central     { One apical spine opposed
    point.                 {   to three basal spines,  396. _Plectaniscus_.

  Four spines arising in two pairs from the poles of
    a common central rod; one apical spine different
    common spines,                                     397. _Periplecta_.
  -----------------------------------------------------------------
  III. Subfamily Hexaplectida. Six radial spines.
  -----------------------------------------------------------------
  Six spines arising from one common central point,    398. _Hexaplecta_.

  Six spines arising in two opposite groups from the
    poles of a common control rod,                     399. _Plectanium_.
  -----------------------------------------------------------------
  IV. Subfamily Polyplectida. Numerous radial spines.
  -----------------------------------------------------------------
  Numerous (seven to nine or more) radial spines
    arising from a common centre (either a central
    point or a branched rod),                          400. _Polyplecta_.



Subfamily 1. TRIPLECTIDA, Haeckel, 1881, Prodromus, p. 424.

_Definition_.--#Plectanida# with three radial spines.



Genus 393. _Triplecta_,[12] Haeckel, 1881, Prodromus, p. 424.

_Definition_.--#Plectanida# with three radial spines, arising from one
common central point and lying in one horizontal plane.

The genus _Triplecta_ is the simplest and most primitive of the Plectanida,
and may therefore be regarded as the prototype of this family. The skeleton
represents a triangular lattice-plate with three radial beams. On the
central union of the latter rests the oral pole of the central capsule.
Since the axis of the latter is vertical, the lattice-plate must be
horizontal, serving for the expansion of the pseudopodia. _Triplecta_ has
arisen from _Triplagia_ by union of the branches of its three radial
spines. In the simplest case only three large meshes are formed,
corresponding probably to the three cortinar meshes in the collar septum of
many #Cyrtellaria#.


1. _Triplecta triangulum_, n. sp.

Spines straight, equal, smooth, cylindrical, each in the basal half with
one pair of divergent straight lateral branches. The opposed branches of
every two neighbouring spines are united by a {922}thin convex bow. In this
way arises a very simple, equilateral triangular skeleton, with three equal
large meshes.

_Dimensions._--Length of the spines 0.14, sides of the triangle 0.16.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


2. _Triplecta triactis_, n. sp. (Pl. 91, fig. 7).

Spines straight, equal, three-sided prismatic, pinnate, each with three to
four pairs of opposite slender pinnulæ or lateral branches; the pinnulæ of
each spine are correspondingly parallel to the main rods of the other two
spines. All pinnulæ branched and connected by a few slender bows, marking
the sides of a regular triangle.

_Dimensions_.--Length of the spines 0.15, sides of the triangle 0.17.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 394. _Plectophora_,[13] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plectanida# with three radial spines, arising from one
common central point and corresponding to the edges of a three-sided
pyramid.

The genus _Plectophora_ has been derived from _Plagiacantha_ by union of
the meeting neighbouring branches of the three radial spines, and exhibits
therefore to it the same relation that _Triplecta_ bears to _Triplagia_.
The loose framework so produced corresponds to the three sides of a flat
pyramid and supports the central capsule.


1. _Plectophora triomma_, n. sp.

Spines equal, straight, three-sided prismatic, thorny, connected by three
convex bows, the meeting branches of lateral spines arising in one pair
from the middle part of each spine. Therefore the skeleton exhibits three
large ovate meshes only.

_Dimensions._--Length of the spines 0.12, of the meshes 0.08.

_Habitat._--North Pacific, Station 238, surface.


2. _Plectophora arachnoides_, Haeckel.

  _Plagiacantha arachnoides_, var., Claparède, 1858, Études sur les
  Infusoires et les Rhizopodes, p. 462, Taf. xxii. fig. 9.

Spines straight, cylindrical, trifid, with one pair of lateral branches.
The nine diverging, straight, and smooth branches are connected in the
distal part by slender concave bows, so that the whole skeleton exhibits
nine wide meshes, three larger pentagonal and six smaller triangular.

_Dimensions._--Length of the spines 0.14, of their branches 0.07.

_Habitat._--North Atlantic, west coast of Norway (Claparède), surface.


{923}3. _Plectophora novena_, n. sp.

Spines slightly curved, three-sided prismatic, thorny, with two pairs of
lateral branches. The six smaller distal branches end freely, whilst the
six larger basal branches are connected by slender convex bows. There are
therefore nine wide meshes, as in the preceding closely allied species.

_Dimensions._--Length of the spines 0.18, of the basal branches 0.08.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream) (John Murray),
surface.


4. _Plectophora pyramidalis_, n. sp.

Spines straight, three-sided prismatic, with three to four verticils of
short lateral branches. The branches of the basal verticils are again
ramified, and form by connecting bows a delicate loose framework, covering
the three sides of a flat pyramid, the three edges of which are the three
radial spines.

_Dimensions._--Length of the spines 0.2, base of the pyramid 0.16.

_Habitat._--Central Pacific, Station 267, surface.



Subfamily 2. TETRAPLECTIDA, Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plectanida# with four radial spines.



Genus 395. _Tetraplecta_,[14] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plectanida# with four equal radial spines, arising from one
common central point and corresponding to the four axes of a tetrahedron.

The genus _Tetraplecta_ has been derived from _Tetraplagia_ by union of the
neighbouring branches of the four radial spines, diverging from a common
point in different directions. In some forms of this genus the four rods
seem to correspond exactly to the four axes, which are directed from the
centre of a tetrahedron towards its four corners; whilst in other forms the
four rods and the angles between them are perhaps not perfectly equal.


1. _Tetraplecta tetrahedra_, n. sp.

Spines straight, equal, three-sided prismatic, pinnate, each with three or
four pairs of opposite straight slender pinnulæ or lateral branches; the
pinnulæ of each side are correspondingly parallel. {924}All pinnulæ
connected by a few slender bridges, thus producing a delicate network with
irregular rhomboidal meshes.

_Dimensions._--Length of the spines 0.15, of the basal branches 0.05.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Tetraplecta quadricornis_, n. sp.

Spines in the basal half straight, in the distal half slightly curved and
irregularly branched, with two to three pairs of unequal alternate lateral
branches, the distal ends of which are connected by a few slender bows,
marking the six edges of an irregular tetrahedron.

_Dimensions._--Length of the spines 0.22, of the basal branches 0.14.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Tetraplecta pinigera_, n. sp. (Pl. 91, fig. 8).

Spines three-sided prismatic, straight, or in the basal half slightly
curved, verticillate; each spine with six to eight three-branched regular
verticils, tapering gradually towards the distal end. All branches of each
spine lie parallel in three equidistant meridian planes, and are connected
by delicate parallel threads, perpendicular to the branches. Therefore the
skeleton consists of four pine-shaped trees and twelve delicate triangular
wings with rectangular meshes.

_Dimensions._--Length of the spines 0.25 to 0.3, of the basal branches 0.1
to 0.15.

_Habitat._--Central Pacific, Station 271, surface.



Genus 396. _Plectaniscus_,[15] nov. gen.

_Definition._--#Plectanida# with four unequal radial spines, arising from
one common central point; one vertical or apical spine opposed to three
divergent or basal spines.

The genus _Plectaniscus_ has probably been derived from _Plagoniscus_ by
reticular union of the neighbouring branches of the four radial spines, and
exhibits therefore to it the same relation that _Tetraplecta_ bears to
_Tetraplagia_. Whilst in these two latter genera the four spines are equal,
in the two former genera there is an important difference between a
vertical spine (or apical horn) and three divergent (commonly larger)
spines, corresponding to the three basal feet of the triradiate
NASSELLARIA. Perhaps, therefore, _Plectaniscus_ is one of the remotest
ancestors of the latter; but differs in the absence of a complete
lattice-shell.


{925}1. _Plectaniscus cortiniscus_, n. sp. (Pl. 91, fig. 9).

Spines straight, three-sided prismatic, with three to four verticils of
short perpendicular branches; the branches of the distal verticils are
simple and free, those of the proximal verticils again ramified and
connected by an arachnoidal network of delicate threads. The vertical
apical spine (or horn) is scarcely one-third or half as long as the three
divergent basal spines (or feet), and the angle between it and the latter
is smaller.

_Dimensions._--Length of the apical spine 0.05 to 0.1, of the three basal
spines 0.18 to 0.2.

_Habitat._--North Pacific, Station 244, surface.


2. _Plectaniscus tripodiscus_, n. sp.

Spines curved, cylindrical, with a variable number of irregular branches,
which in the distal half of the spines are free, in the basal half again
ramified and connected by a loose spongy framework. The apical spine is
shorter and simpler, nearly straight, less ramified.

_Dimensions._--Length of the apical spine 0.1, of the three basal spines
0.15 to 0.18.

_Habitat._--North Pacific, Station 238, surface.


3. _Plectaniscus archiscenium_, n. sp.

Spines slightly curved, three-sided prismatic, with two to three verticils
of short curved branches. The vertical apical spine is about twice as long
as the three basal spines, and connected with them by an irregular loose
framework. The three basal spines are connected together only by a simple
ring, so that between them remain three large collar holes, like those of
the similar and closely allied _Archiscenium quadrispinum_ (Pl. 53, fig.
11).

_Dimensions._--Length of the apical spine 0.32, of the three basal spines
0.18.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


4. _Plectaniscus cladoscenium_, n. sp.

Spines curved, three-sided prismatic. The three basal spines pinnate, with
four to five pairs of opposite curved pinnulæ; the distal pairs are simple
and free, the basal pairs branched and connected by an irregular delicate
framework, which together with the apical spine forms a spongy cap-shaped
shell, similar to _Cladoscenium_. Apical spine about half as long, simple.

_Dimensions_.--Length of the apical spine 0.1, of the three basal spines
0.18.

_Habitat._--Central Pacific, Station 274, surface.


5. _Plectaniscus clathrocorys_, n. sp.

Spines straight, three-sided prismatic, with seven or eight verticils of
ramified branches, which in the basal half are connected by an irregular
loose framework. In the distal half each of the three divergent basal
spines (or feet) is connected with the longer apical spine (or horn) by a
{926}fenestrated triangular lattice wing. Therefore the skeleton becomes
very similar to _Clathrocorys_ (Pl. 64, figs. 8-10), but wants the regular
central cephalis.

_Dimensions._--Length of the apical spine 0.2, of the basal spines 0.14.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 397. _Periplecta_,[16] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plectanida# with four unequal radial spines, arising in
pairs from the two poles of a common central rod; one ascending apical
spine opposed to three descending basal spines.

The genus _Periplecta_ has probably been derived from _Plagiocarpa_ (by
concrescence of the meeting spine branches), and has the same important
relation to a part of the triradial #Stephoidea# (_Cortina_, &c.) and
#Cyrtoidea# (_Pteroscenium_, &c.). It differs from the latter only in the
fact that the loose irregular framework connecting the bases of the four
cortinar spines is not a regular lattice-shell.


1. _Periplecta cortina_, n. sp. (Pl. 91, fig. 10).

Spines of very different size and shape, three-sided prismatic. The apical
spine (or horn) is larger, nearly straight, and bears a verticil of three
large divergent branches, which are again ramified. The three basal spines
(or feet) are curved, pinnate, each with three to five pairs of opposite
simple curved branches. A small common central rod separates the two united
pectoral feet from the two other spines (the caudal foot and the apical
horn). The three basal feet are connected by three convex bows composing a
horizontal collar ring, and since the central rod is prolonged between the
pectoral feet to the ring, a very remarkable collar septum is formed with
four cortinar meshes. Above this septum an irregular spongy shell,
including the central capsule, is formed by a delicate framework,
interwoven between the apical horn and the three basal feet.

_Dimensions._--Length of the apical spine 0.25 to 0.3, of the three basal
spines 0.15 to 0.2.

_Habitat._--Central Pacific, Station 271, surface.


2. _Periplecta pteroscenium_, n. sp.

Spines of very different size and shape, three-sided prismatic,
verticillate. The apical spine (or horn) with ten to twelve verticils, is
one and a half times as long as the three basal spines (or feet), which
bear six to eight verticils only; each verticil with three branches which
by communicating ramules form a loose irregular wickerwork. Similar to
_Pteroscenium pinnatum_, Pl. 53, figs. 14-16, but without a regular
lattice-shell. A short basal central rod separates two equal (pectoral)
spines from two unequal spines, the larger of the latter is the apical, the
shorter the caudal spine.

_Dimensions._--Length of the apical spine 0.26, of the three basal spines
0.17.

_Habitat._--Central Pacific, Station 274, surface.


{927}3. _Periplecta monocyrtis_, n. sp.

Spines of nearly equal size and shape, cylindrical, irregularly branched.
The apical spine is straight, more branched and nearly twice as long as the
three basal spines. All four spines in the basal third connected by a loose
spongy framework, approaching the form of some Monocyrtida.

_Dimensions._--Length of the apical spine 0.24, of the basal spines 0.13.

_Habitat._--Central Pacific, Station 274, surface.



Subfamily 3. HEXAPLECTICA, Haeckel.

_Definition._--#Plectanida# with six radial spines.



Genus 398. _Hexaplecta_,[17] Haeckel, 1881, Prodromus, p. 425.

_Definition._--#Plectanida# with six radial spines, arising from one common
central point.

The genus _Hexaplecta_ has probably been derived from _Hexaplagia_ by
concrescence of the meeting branches of the six spines, and therefore has
to it the same relation that _Plectophora_ bears to _Plagiacantha_. The two
species here described represent perhaps two different genera, since in the
first all six spines are equal, opposed in pairs, in the second different
in pairs (three upper smaller and three lower larger).


1. _Hexaplecta triaxonia_, n. sp.

Spines equal, opposite in three crossed pairs, straight, three-sided
prismatic, thorny, in the distal half with three leaf-shaped, dentate
edges, in the basal half with three verticils of slender branches, which
are connected by parallel threads, and so form an arachnoidal network with
rectangular or rhomboidal meshes.

_Dimensions._--Length of the spines 0.22, of their basal branches 0.06.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.


2. _Hexaplecta tricladonia_, n. sp.

Spines unequal, three larger spines (in the lower half of the body) being
opposite to three smaller spines (in the upper half). The latter are nearly
horizontally expanded, each bearing three straight divergent branches. The
larger are stronger, twice as long and armed with three verticils, each of
three branches. All six spines are slender, three-sided prismatic. Their
branches are very thin, thread-shaped, and form by their union a loose
network with irregular polygonal meshes.

_Dimensions._--Length of the larger spines 0.25, of the smaller 0.12.

_Habitat._--South Pacific, Station 291, surface.



{928}Genus 399. _Plectanium_,[18] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plectanida# with six radial spines, arising in two opposite
divergent groups from the two poles of a common central rod.

The genus _Plectanium_ has been derived from _Plagonium_ by concrescence of
the meeting branches, and bears therefore to it the same relation that the
preceding _Hexaplecta_ exhibits to _Hexaplagia_. Whilst in these two latter
genera the six spines arise from a common central point, they arise here in
two divergent groups from the two poles of a horizontal common middle rod,
similar to the spicula of many #Beloidea#.


1. _Plectanium trigeminum_, n. sp. (Pl. 91, fig. 11).

Spines straight and stout, six to eight times as long as the common middle
rod, three-sided prismatic; in the distal half thickened, with three
divergent terminal thorns; in the basal half with three to four verticils
of thin lateral branches, which are again ramified, and by their united
threads produce an irregular loose framework.

_Dimensions._--Length of the spines 0.25, basal breadth 0.005, terminal
breadth 0.02; length of the middle rod 0.03.

_Habitat._--North Pacific, Station 244, surface.


2. _Plectanium ovodimare_, n. sp.

Spines straight and stout, three-sided prismatic, about four times as long
as the common middle rod, gradually thinned towards the distal end; in the
basal half with two to three verticils of forked branches, which are
dichotomously ramified, and by their united threads form a loose ovate
framework.

_Dimensions._--Length of the spines 0.17, of the middle rod 0.04.

_Habitat._--North Pacific, Station 236, surface.


3. _Plectanium sphærozoum_, n. sp.

Spines straight, cylindrical, ten to twelve times as long as the common
middle rod, with six to eight verticils of thorny branches, tapering
towards the distal end; the branches of the verticils are simple in the
distal half, again ramified in the basal half, and here connected together
by irregularly branched threads forming a loose framework. (Resembles one
spiculum of _Sphærozoum verticillatum_, Pl. 4, fig. 7, but is more richly
branched, with united ramules.)

_Dimensions._--Length of the spines 0.2, of the middle rod 0.01.

_Habitat._--Central Pacific, Station 266, surface.



{929}Subfamily 4. POLYPLECTIDA, Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Plectanida# with numerous (seven to nine or more) radial
spines.



Genus 400. _Polyplecta_,[19] Haeckel.

_Definition._--#Plectanida# with numerous (seven to nine or more) radial
spines, arising from a common centre and lying in different planes.

The genus _Polyplecta_ comprises provisionally all Plectanida possessing
seven or more radial spines, united in the centre of the framework. It may
be derived from _Polyplagia_ by meeting and concrescence of the free
branches. But as in the latter genus, here also the few observed species
are very different, perhaps of different origin, and may be afterwards
better separated as representatives of diverse genera.


1. _Polyplecta heptacantha_, n. sp. (Pl. 91, fig. 12).

  _Heptaplegma heptacantha_, Haeckel, 1882, MS.

Seven unequal spines divergent from one common central point, slender,
slightly curved, three-sided prismatic. Four spines are much larger, twice
to three times as long and as thick as the three smaller spines. One of the
four larger spines is directed upwards (as "apical horn"), whilst the three
others diverge downwards (as "basal feet"). Each of the four larger spines
bears five to seven equidistant verticils of three divergent branches, the
proximal of which are branched, the distal simple. The three smaller spines
lie nearly horizontally, midway between the odd apical spine and the three
basal spines, and in the same meridian planes with them; each bears one
verticil of three divergent branches. All the branches are united by
arachnoidal threads, composing a loose wickerwork with irregular, generally
quadrangular meshes.

_Dimensions._--Length of the four larger spines 0.27 to 0.33, of the four
smaller 0.1 to 0.14.

_Habitat._--Central Pacific, Station 271, surface.


2. _Polyplecta enneacantha_, n. sp.

  _Enneaplegma enneacantha_, Haeckel, 1881, Prodromus, p. 425.

Nine equal and equidistant, straight, cylindrical radial spines, lying
nearly in one plane, arise from an irregular spongy central framework; six
of them seem to be secondary, intercalated between three equidistant
primary spines, which are united in the centre. (This species resembles in
the nine-radial structure the remarkable _Enneaphormis rotula_, Pl. 57,
fig. 9, and may perhaps be derived from a similar species; but it has no
regular latticed shell.)

_Dimensions._--Length of the spines 0.22, diameter of the framework 0.17.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


{930}3. _Polyplecta decacantha_, n. sp.

  _Pentaplegma decacantha_, Haeckel, Prodromus, p. 425.

Ten radial spines, curved, cylindrical, irregularly branched, diverge in
different directions and seem to arise in pairs from an irregular central
framework, in the centre of which five primary spines are united; the
latter correspond probably to the five spines of _Pentaspyris_, &c. The
density of the spongy central framework did not allow of an accurate
investigation, and makes it doubtful whether this species is not a
_Spongiomma_.

_Dimensions._--Length of the spines 0.3 to 0.4, diameter of the framework
0.18.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.


4. _Polyplecta polybrocha_, Haeckel.

  ? _Acanthodesmia polybrocha_, Haeckel, 1865, Zeitschr. f. wiss. Zool.,
  Bd. xv. p. 368, Taf. xxvi. fig. 3.

  _Plegmosphæra polybrocha_, Haeckel, 1881, Prodromus, p. 455.

Numerous (twenty to thirty or more) radial spines, thin, cylindrical,
curved and irregularly branched, arising from an irregular central spongy
framework, are connected by numerous slender arches. The specimen observed
by me in 1880 in Portofino was a true _Polyplecta_, with three primary
spines centrally united, between which numerous other spines were
intercalated. The similar specimen, however, observed in 1864 in
Villafranca, and figured, _loc. cit._, was perhaps a _Plegmosphæra_.

_Dimensions._--Length of the radial spines 0.05 to 0.1, diameter of the
framework 0.16.

_Habitat._--Mediterranean (Villafranca, Portofino), surface.


5. _Polyplecta dumetum_, Haeckel.

  _Acanthodesmia dumetum_, J. Müller, 1868, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 30, Taf. i. Fig. 3.

Numerous (ten to twelve or more) radial spines, thin and straight, with a
few straight lateral branches, diverge in different directions and are
connected by a few slender curved arches. Some similar forms, but more
developed, with numerous branches and curved rods, are found in the Pacific
Radiolarian ooze, and represent probably different species.

_Dimensions._--Length of the radial spines 0.05 to 0.08, of the branches
0.02 to 0.03.

_Habitat._--Mediterranean, French shore (Cette and Saint Tropez), Johannes
Müller, surface.


{931}----


Suborder III. STEPHOIDEA, Haeckel.

  _Stephoidea_ vel _Stephida_, Haeckel, 1881, Prodromus, p. 444.
  _Acanthodesmida_ (_sensu ampliori_), Bütschli, 1882, Zeitschr. f. wiss.
      Zool., vol. xxxvi. p. 495.

_Definition._--NASSELLARIA without complete lattice-shell, with a skeleton
composed of one or more simple rings, which may be united by a loose
framework and are separated by large openings or gates. One primary or
sagittal ring, determining the sagittal or median plane of the bilateral
body, encloses the monaxonian central capsule.

The suborder #Stephoidea#, hitherto known by a few species only of
"Acanthodesmida," comprises a large number of interesting NASSELLARIA (now
more than two hundred species), which possess peculiar interest for the
morphology and phylogeny of this legion. The monaxonian central capsule of
the #Stephoidea# is surrounded either by one simple ring or by a complex
system of several loosely connected rings; these may be united by a loose
framework of connected branches, but never produce a complete
lattice-shell, as is constantly the case in the #Spyroidea#, #Botryodea#,
and #Cyrtoidea#. Therefore there remain between the parts of the connected
rings a few large openings which we call "gates," separating them from the
numerous small "pores" of the complete lattice-shells. In the most simple
case, if only one ring be formed, there is also present only one "gate,"
the aperture of this simple ring.

The first known species of #Stephoidea# were observed in the Mediterranean
by Johannes Müller in 1856, and described and figured in his last treatise
(1858) under the names _Lithocircus annularis_ (_loc. cit._, Taf. i. fig.
1) and _Acanthodesmia vinculata_ (_loc. cit._, Taf. i. figs. 4-7). In the
following year I myself observed two other living species in the
Mediterranean, and described them in my Monograph (1862, pp. 268, 270) as
_Zygostephanus mülleri_ (Taf. xii. fig. 2) and _Prismatium tripleurum_
(Taf. iv. fig. 6). For these four longest known #Stephoidea# I founded the
new family of Acanthodesmida (_loc. cit._, p. 265), but united with them
two other similar genera which I afterwards separated:--_Plagiacantha_
(belonging to the #Plectoidea#) and _Dictyocha_ (belonging to the
PHÆODARIA).

When, in 1876, I received the rich material of the Challenger collection, I
was astonished to find in it an enormous number of new, similar, and partly
very interesting "Acanthodesmida," which were afterwards arranged in my
Prodromus (1881, p. 444) in thirty-eight different genera and four
"subfamilies," all united in one single large family, "Stephida or
Monopylaria cricoidea." I retain here this natural group in the same sense,
but give to it the rank of a "suborder," separating at the same time its
four subfamilies as substantial "families." Since the names of the
{932}latter, proposed in the Prodromus, were not quite suitable, I replace
them here by the following more convenient names:--

  1. Family Stephanida (= Monostephida, 1881, p. 447). Skeleton entirely
  formed by one simple ring (the primary vertical sagittal ring). The only
  "gate" is the simple aperture of the ring.

  2. Family Semantida (= Dyostephida, 1881, p. 446). Skeleton composed of
  two rings, perpendicular to one another; the primary vertical sagittal
  ring bears at the base a horizontal basal ring; between the two rings two
  or more "basal gates remain."

  3. Family Coronida (= Triostephida, 1881, p. 445). Skeleton composed of
  two crossed vertical or meridional rings, perpendicular to one
  another--the primary sagittal ring and the secondary frontal ring.
  Commonly the two vertical rings are united at the base by a horizontal
  basal ring, and between them remain two or more "basal gates."

  4. Family Tympanida (= Parastephida, 1881, p. 446). Skeleton composed of
  two parallel horizontal rings, and upper mitral ring, and a lower basal
  ring, both connected by vertical or divergent columellæ, which are parts
  of vertical rings (primary sagittal, and secondary frontal ring).

The peculiar structure of the central capsule of the #Stephoidea#, and
their character as true MONOPYLEA, were first recognised by Richard
Hertwig, who in 1879, in his Organismus der Radiolarien, gave an excellent
detailed description of it (_loc. cit._, pp. 68-72, Taf. vii. figs. 4, 5).
He also pointed out the near affinity of these "Acanthodesmida" with the
#Spyroidea# or Zygocyrtida, uniting the latter with the former family.

A fuller explanation of this affinity, and of the morphological and
phylogenetic importance of the "Acanthodesmida," as ancestral forms of the
#Spyroidea# and #Cyrtoidea#, was given in 1882 by Bütschli (Zeitschr. f.
wiss. Zool., vol. xxxvi. pp. 495-501). He described in detail some
important fossil forms of Acanthodesmida as different species of
"_Stephanolithis_," a name which Ehrenberg had employed for various
ring-like fragments of Radiolarian shells, sponges, and other fossil
bodies. The four fossil species which Bütschli described represent four
different genera of #Stephoidea#, viz., _Semantis_ (_spinescens_),
_Semantrum_ (_mülleri_), _Semantidium_ (_haeckelii_), and _Tristephanium_
(_hertwigii_). On the phylogenetic conclusions, derived from these accurate
observations, compare above, p. 893, &c. The topographical signification of
the parts, employed by Bütschli, is contrary to mine; he calls my dorsal
side the "anterior," and my ventral side the "posterior."

The geometrical fundamental form of the body in nearly all #Stephoidea#
(with few exceptions) is distinctly bilateral or "dipleuric," so that we
can easily distinguish the {933}three different dimensive axes: the
principal axis with different apical and basal poles, the sagittal axis
with different dorsal and ventral poles, and the lateral axis with
equivalent right and left poles. In only a few genera this bilateral
symmetry is not expressed, and a simpler, more regular fundamental form
appears. The latter may be either primary (in the monaxonian _Archicircus_
and _Lithocircus_) or secondary, afterwards acquired (in the octahedral
_Trissocircus_ and _Trissocyclus_, the cubical _Lithocubus_, the prismatic
_Eutympanium_, and some other forms).

The most important element of the skeleton, with which the formation
begins, in all #Stephoidea# is the simple primary or sagittal ring, lying
vertically in the sagittal or median plane of the body and surrounding the
monaxonian central capsule. This sagittal ring is the only essential
element of the skeleton in all Stephanida, and is completely preserved in
all Semantida, also in the greater part of the Coronida and Tympanida. It
is partially reduced in the small groups of the true Acanthodesmida
(subfamily of Coronida) and the Dystympanida and Eutympanida (subfamilies
of Tympanida). Here only the vertical parts of it are preserved (dorsal and
ventral rod), whilst the horizontal parts are lost (mitral and basal rod).

The sagittal ring lies constantly in the vertical median plane of the body,
and therefore divides the enclosed central capsule into a right and a left
half. It is rarely regular or subregular, commonly dipleuric or distinctly
bilateral, so that we may easily distinguish its dorsal and ventral, apical
and basal parts. The most important of these four parts or "rods" is the
"basal rod" or the inferior part, because here the ring is in closer
connection with the central capsule and its "porous area"; here peculiar
spines or branches are commonly developed, which even on the isolated ring
immediately determine the basal pole. The opposite upper part, or the
"mitral rod," is also often distinguished by the peculiar appendages. The
posterior part, or the "dorsal rod" (the anterior rod, _a_, in the
description of Bütschli), is commonly more straight, often quite vertical.
The opposite anterior part, or the "ventral rod" (the posterior rod, _b_,
of Bütschli), is usually more convex, and often strongly curved or
semicircular.

Whilst this dipleuric or bilateral (commonly obliquely ovate or nearly
triangular) form of the sagittal ring is distinctly preserved in by far the
greater number of #Stephoidea#, it is replaced in some few genera by a more
regular, amphithect, diphragmatic, or biradial form. In this case we may
often suppose a primary regularity to exist, the dorsal and ventral parts
being not yet differentiated, as in _Archicircus_ and _Lithocircus_,
_Zygostephanus_ and _Protympanium_, and perhaps also in some other forms.
But in other cases the regularity is, on the contrary, secondary, being
derived from original bilateral forms.

The rod of the sagittal ring is either cylindrical (with circular
transverse section) or angular (commonly with triangular transverse
section). In nearly all #Stephoidea# (with very few exceptions) branches or
apophyses are developed from the ring, regularly disposed and often of
great morphological importance. Commonly these {934}apophyses are developed
in pairs, growing symmetrically on both sides of the ring. The most
important of these apophyses are:--(1) Basal apophyses, arising from the
basal hole of the ring; (2) mitral apophyses, arising from the apical pole;
(3) dorsal apophyses, arising from the middle of the dorsal rod; and (4)
ventral apophyses, arising from the middle of the ventral rod. The two
former arise in the principal axis, the two latter in the sagittal axis of
the body. Very frequently the latter pair is replaced by two pairs of
transverse branches, one inferior (mandibular) and one superior (orbital).
The apophyses of the ring are either simple or branched, often very large,
richly ramified, and give origin to a number of further products.

Whilst in the Stephanida the primary sagittal ring alone represents the
whole skeleton, it produces in all other #Stephoidea# one or more secondary
rings. The most important of these is the horizontal basal ring, appearing
first in the Semantida (Pl. 92). From the base of the sagittal ring there
arise in the horizontal basal plane two pairs of lateral branches or "basal
apophyses." The curved opposite branches of the corresponding pairs become
united on each side of the primary ring (right and left), and so produce a
second, horizontal ring, perpendicular to the former. This basal ring
encloses two paired basal gates, which are enclosed on the medial side by
the basal rod of the sagittal ring, and on the lateral side by two united
apophyses (_Semantis_, Pl. 92, figs. 1, 2). These two primary basal gates
are of the greatest morphological importance; we call them the "jugular
gates or jugular pores" (in the description of Bütschli, the pores I, _loc.
cit._, p. 498). The dorsal pair of basal apophyses (on their posterior
edge) are the coracal rods, _e_ (rods _e_ of Bütschli); the opposite
ventral pair (on their anterior edge) are the clavicular or furcular rods,
_f_ (rods _e_1 of Bütschli); compare Pls. 92-95, and their explanation.

The skeleton of _Semantis_, the prototype of the Semantida, thus assumes
the characteristic form of a signet-ring. The basal ring enclosing the two
jugular pores corresponds to the seal-plate. It is commonly more or less
horizontal; but often the apophyses descend obliquely (Pl. 92, figs. 1, 2,
13, &c.), more rarely laterally (Pl. 29, fig. 11). The further development
of this typical form is essentially effected by the production of new basal
pores in the horizontal seal-plate. In _Semantrum_ (Pl. 92, figs. 3, 4, 5)
we find already four basal gates. Behind the jugular gates is formed a
second pair, the "cardinal gates" (pores II of Bütschli). These are
enclosed on the anterior margin by the coracal rods (_e_), on the posterior
margin by the scapular rods (_d_), a third pair of basal apophyses, arising
behind the former from the sagittal ring and uniting with them (the rods
_e_2 of Bütschli). Commonly the two posterior, or cardinal gates are much
larger than the two anterior, jugular gates. This characteristic basal
plate of _Semantrum_, with two pairs of basal pores, is of the greatest
morphological importance, as it is inherited in by far the greater number
of the NASSELLARIA, though not so generally as Bütschli supposes. The basal
ring of _Semantrum_ is either more circular {935}or elliptical, or more
polygonal, and is connected with the basal rod of the sagittal ring by
three pairs of radial apophyses, the anterior furcular, the middle coracal,
and the posterior scapular rods.

A third important form of Semantida is _Semantidium_ (Pl. 92, figs. 6, 7).
Here we find three pairs of basal pores in the seal-plate; the third pair,
newly formed, consists of the cervical gates (_e_), bounded in front by the
scapular rods (_d_), behind by a fourth pair of basal apophyses, the
cervical rods.

The basal apophyses of the sagittal ring are not only of great
morphological importance, because they produce by their union three typical
pairs of basal gates or "collar pores," but also because their
prolongations often appear as typical basal feet. The distal prolongations
of the coracal rods appear in _Semantiscus_ (Pl. 92, figs. 16-18) as two
pectoral feet, those of the scapular rods as two tergal feet, whilst the
opposite prolongations of the basal rod of the sagittal ring appear as two
"sagittal feet" (in front an anterior or sternal, and behind a posterior or
caudal foot). In the typical _Cortiniscus_ (Pl. 92, figs. 11-13) only three
feet are developed; an odd caudal and two paired pectoral feet (compare
above, p. 891). The typical basal ring of the Semantida, with its paired
basal gates (_Semantis_), reappears in the majority of the Coronida,
differing from the former in the development of a second vertical ring,
which lies in the frontal plane (perpendicular to the sagittal ring), and
which we therefore call the frontal ring. In only one small group of the
Coronida the basal ring is absent, namely, in the Zygostephanida, and here
the frontal ring appears in the simplest form, as a complete elliptical
meridian ring, crossing the sagittal ring perpendicularly on the two poles
of the main axis (_Zygostephanus_, Pl. 93, figs. 1-4), Four large lateral
gates between the two rings remain open. This form may be derived directly
from the Stephanida in the following way; from both poles of a simple
sagittal ring there arise two opposite lateral apophyses, which in the
frontal plane become curved one towards the other, and united in the poles
of the transverse axis. The basal apophyses would be the coracal rods. But
it is also possible that _Zygostephanus_ was derived from _Semantis_ by the
loss of the furcular rods.

The three typical rings (or the "dimensive rings") of the #Stephoidea#
appear in their most complete form in the subfamily Trissocyclida (Pl. 93,
figs. 7, 13). Here all three rings are undivided and completely developed
in the three dimensive planes, perpendicular one to another. Between them
there remain eight large open gates; the four superior are the four
"lateral gates" of _Zygostephanus_, the four inferior are the four basal
gates of _Semantrum_. The four latter are originally much smaller than the
four former; but in _Trissocircus_ and _Trissocyclus_ (Pl. 93, figs. 10-12)
they reach the same size. Therefore all eight gates are here of equal form
and similar size, and the basal ring, now a true equatorial ring, divides
the two meridional rings into two equal halves.

In the Eucoronida, a third subfamily of Coronida, the sagittal and the
basal rings {936}are complete, but the frontal ring is incomplete, its
basal part being wanting (Pl. 82, figs. 4-6). Therefore we find here six
large gates between the three rings; four upper lateral gates (between the
two crossed vertical rings) and two lower basal gates (between the basal
rod of the sagittal ring and the two halves of the basal ring).
_Eucoronis_, the type of this subfamily, may be derived either directly
from _Semantis_ by development of a frontal ring, or from _Tristephanium_
by loss of the basal part of the frontal ring.

A quite simple basal ring with a single gate, distinguishes the fourth
subfamily of Coronida, the Acanthodesmida (_sensu restricto_), the genera
_Coronidium_ (Pl. 82, figs. 1, 2, 7, 8) and _Acanthodesmia_ (Pl. 93, fig.
5). The horizontal basal ring alone is here complete, whilst both vertical
rings (the sagittal and frontal rings) are incomplete, their basal parts
being wanting. Therefore there are here five gates, four lateral and one
basal. These forms may be derived from _Eucoronis_ by loss of the basal rod
of the primary sagittal ring.

The Tympanida, the fourth family of #Stephoidea#, exhibit another type of
ring structure. Here two parallel horizontal rings are constantly
developed, one on the apical pole, the other on the basal pole of the
sagittal ring. The latter is the same basal ring as in the Semantida and
Coronida. The former is a "mitral ring," developed in the same manner, by
union of two pairs of horizontal lateral branches, which arise on both
sides from the apical rod (or mitral rod) of the sagittal ring. In the
simplest case these two parallel horizontal rings are connected only by the
sagittal ring, which is either complete (_Protympanium_, Pl. 93, fig. 14)
or incomplete (_Parastephanus_, Pl. 93, fig. 21). But commonly also an
incomplete frontal ring is present, so that the two horizontal rings are
connected by four vertical or subvertical rods; two of these "columellæ"
are the dorsal and ventral rods of the sagittal ring, the two others are
the lateral rods of the frontal ring. Between the former and the latter are
sometimes developed two, four, or more accessory columellæ (probably halves
of accessory incomplete diagonal meridian rings). In this way arise the
characteristic "drum-forms" of many Tympanida, in which the two parallel
horizontal rings correspond to the upper and lower rings of a drum, whilst
the connecting vertical columellæ correspond to its parallel lateral rods
(Pl. 83, figs. 1, 2, &c.).

Originally the two horizontal rings of these "drum-shells" are both
bisected by the complete sagittal ring, each provided with two lateral
gates (Protympanida). But in the Eutympanida both rings exhibit one simple
gate only, the apical and the basal rod of the sagittal ring being lost. In
the Paratympanida both rings are closed by a secondary lattice-plate whilst
in the Dystympanida the upper (mitral) ring alone is closed by such a
plate, the lower (basal) ring is open. In some Eutympanida the shell
assumes the strange form of a regular geometrical cube, the twelve edges of
which are represented by thin rods of silex (_Lithocubus_)--its four upper
edges represent the mitral ring, the four lower the basal ring; two
opposite of the four vertical {937}cube-edges are the lateral halves of the
frontal ring, the two other alternate ones are the remaining halves of the
reduced sagittal ring (dorsal and ventral rod) (Pl. 82, fig. 12).

In many Tympanida and Coronida a loose irregular lattice or framework is
developed, which partly closes the large open gates. But this never reaches
the completeness of a true lattice-shell, such as we find in the
#Spyroidea#, #Botryodea#, and #Cyrtoidea#. In by far the greater number of
#Stephoidea# the corners, and partly also the rods, of the shell are armed
with numerous irregular spines, often forked or richly branched. Among
these spines the descending "basal apophyses" possess a peculiar
importance, since by their regular number and disposition they correspond
to the radial rods of the #Plectoidea#, and to the typical "feet" of the
#Spyroidea# and #Cyrtoidea#. The most important of them are the three
cortinar feet (one caudal and two pectoral) of _Cortina_, _Cortiniscus_,
&c. (compare above, p. 891).

_The Central Capsule_ exhibits in the #Stephoidea# the same characteristic
structure as in all other MONOPYLEA, first exactly pointed out by Richard
Hertwig in 1879 (Organismus der Radiol., p. 71, Taf. vii. figs. 4, 5). Its
form is commonly ovate or ellipsoidal, sometimes also lentelliptical or
nearly spherical. It exhibits constantly on the basal pole the porochora or
porous area, and in the basal half the podoconus or pseudopodial cone. From
the surrounding sagittal ring it is separated by a thick jelly-like
calymma, which commonly exhibits numerous zooxanthellæ. The numerous
pseudopodia are commonly branched, with rather rare anastomoses. The
membrane of the central capsule is thick.

_Synopsis of the Families of_ #Stephoidea#.

  I. Skeleton composed of the simple vertical sagittal ring
    only, without secondary rings,                           1. STEPHANIDA.

  II. Skeleton composed of two crossed rings, a vertical
    sagittal and a horizontal basal ring,                    2. SEMANTIDA.

  III. Skeleton composed of two crossed vertical meridional
    rings (a primary sagittal and a secondary frontal ring),
    commonly also with a horizontal basal ring,              3. CORONIDA.

  IV. Skeleton composed of two parallel horizontal rings
    (upper mitral and lower basal ring), both connected by
    a vertical sagittal ring (and often by a vertical
    frontal ring),                                           4. TYMPANIDA.



Family XLVIII. #STEPHANIDA#, Haeckel (Pl. 81).

  _Monostephida_, Haeckel, 1881, Prodromus, p. 447.

_Definition_.--#Stephoidea# with a simple sagittal ring, without any
lattice-work.

The family #Stephanida# is the most simple of all #Stephoidea#, and
probably the common ancestral group of this suborder (compare above, p.
933). The skeleton {938}consists of a simple ring only, surrounding the
central capsule, and armed commonly with simple thorns or with larger
branched spines. The branches of these spines are constantly free, never
joining together. Therefore the shell exhibits no trace of fenestration or
lattice-work, no pores or gates, except the simple large gate of the ring
itself. In all other #Stephoidea# we find secondary gates or lattice-work.

The first known form of this family is _Lithocircus annularis_, described
by Johannes Müller in 1858 (Abhandl. d. k. Akad. d. Wiss. Berlin, p. 29,
Taf. i. fig. 1). He observed already the central capsule ("Blase")
surrounded by the circular ring of silex, and the calymma ("Strahlige
Gallert") enveloping the whole body. The peculiar structure of the soft
body, particularly the "area porosa" on the basal pole of the central
capsule, and the pseudopodial cone within it, were first accurately
described by Hertwig (in 1879). A great number of simple rings, similar to
these, were found in the Challenger collection, and are here arranged in
six genera and forty-eight species.

The simple ring of silex, which alone forms the skeleton of the Stephanida,
corresponds to the primary or sagittal ring of the other #Stephoidea#, and
lies therefore vertically in the median or sagittal plane of the body. We
can therefore distinguish on it four different segments, rods or bows, two
of which are more horizontal, two more vertical. The former are one upper
bow or apical rod, and one lower bow or basal rod. The latter are one
posterior bow or dorsal rod, and one anterior bow or ventral rod. Sometimes
each of these four component bows is distinguished by a corner-spine, or by
a pair of divergent branches.

In the two simplest (and probably oldest) genera of Stephanida, in
_Archicircus_ and _Lithocircus_, the dorsal and ventral rods of the ring
are equal and cannot be distinguished; therefore the fundamental form is
here amphithect, diphragmatic, or biradial (the poles of the sagittal axis
being equal). In the four other genera the dorsal rod is more straight
(often vertical) and more or less different from the ventral, convexly
curved rod; therefore the fundamental form is here dipleuric or bilateral,
as in the greater number of all NASSELLARIA (the poles of the sagittal axis
being unequal). The general form of the ring in this latter case is
commonly obliquely ovate or nearly triangular, the basal pole being more
pointed, the apical pole more rounded (Pl. 81).

The rods or bows of the ring are either roundish or cylindrical (with
circular or elliptical transverse section), or they are prismatic or
angular (commonly with triangular transverse section). In the latter case
one edge usually is prominent in the sagittal plane (on the convex outside
of the ring), whilst two other edges diverge laterally on both sides of it.
The inner or concave margin of the ring is commonly smooth.

The inner perimeter of the large gate, enclosed by the ring, is commonly
rounded (elliptical or ovate), rarely angular. However, the outer perimeter
of the ring is {939}nearly always polygonal, with prominent corners, and
usually from these arise thorns or branched spines which are regularly
disposed. Regarding this disposition we may distinguish three cases: A, the
spines lie in the sagittal plane and form a single row, arising from the
median edge; B, the spines lie on both sides of the latter and form two
parallel rows, arising from the two lateral edges; C, the spines represent
a combination of A and B, and are disposed in three rows, two paired rows
arising from the two lateral edges, and an odd middle row between them,
arising from the median edge. The spines are simple, without branches, in
_Archicircus_ and _Zygocircus_; more or less branched in _Lithocircus_ and
_Dendrocircus_. The branches are often richly ramified or arborescent, and
exhibit great variety in size, special form, and direction (compare Pl.
81).

The number and disposition of the spines or groups of spines are usually
constant, and may be employed in the further progress of our knowledge, to
distinguish a number of genera and subgenera. Very commonly (perhaps in the
majority of the Stephanida) we find six groups of spines, an apical group
on the upper rod of the sagittal ring, a basal group on the lower rod (on
the porochora of the central capsule), two ventral groups on the anterior
rod, and two dorsal groups on the posterior rod. In other species we find
four or eight groups instead of six, and sometimes a larger number.

The most important of these apophyses of the ring are the basal spines,
arising from its basal pole, where the porochora of the central capsule
rests upon it. They are often much larger and more branched than the other
spines, and attain a peculiar morphological value in the small subfamily
Cortinida. Here we find three or four regularly disposed "basal spines,"
which may be compared to the typical "basal feet" of the #Cyrtellaria#,
appearing in the majority of #Spyroidea# and #Cyrtoidea#. _Cortina_, one of
the most important NASSELLARIA, bears three typical divergent feet on the
base of the simple ring, two paired anterior or "pectoral feet," and an odd
posterior or "caudal foot." The latter appears as a direct basal
prolongation of the dorsal rod of the ring, and is opposed to an upper
prolongation of the same, which corresponds to the "apical horn" of the
#Cyrtellaria# (Pl. 97, figs. 1-3). As already explained above, these three
basal feet of _Cortina_ possess the highest phylogenetic value, since they
may also be compared with the three primary radial spines of the
#Plectoidea#, and so connect the #Cyrtellaria# and the #Plectellaria#.
_Stephanium_ differs from _Cortina_ in the possession of four basal feet,
an odd anterior or "sternal foot" being added to the three typical feet of
the latter (Pl. 92, figs. 20, 21). Some forms of #Plectoidea#
(_Plagoniscus_, _Plectaniscus_, &c.) seem to be nearly related to these
Cortinida, and may be easily transformed into them by development of a
complete ring, embracing the central capsule. They seem to demonstrate the
near affinity of all these triradiate NASSELLARIA (Pl. 91, figs. 4, 5, 9,
10).

{940}_Synopsis of the Genera of Stephanida._

  -------------------------------------------------------------------------
  I. Subfamily Lithocircida.
     No typical basal feet on the base of the ring (no cortinar feet).
  -------------------------------------------------------------------------
  Ring diphragmatic or   { Ring smooth or thorny,
    amphithect; dorsal   {   without branched spines.  401. _Archicircus_.
    and ventral bow      {
    equal.               { Ring armed with branched
                         {   spines,                   402. _Lithocircus_.

  Ring dipleuric,        { Ring smooth or thorny,
    bilateral; dorsal    {   without branched spines,  403. _Zygocircus_.
    and ventral bow      {
    different.           { Ring armed with branched    404. _Dendrocircus_.
                         {   spines.
  -------------------------------------------------------------------------
  II. Subfamily Cortinida.
      Three or four typical basal feet on the ring (cortinar feet).
  -------------------------------------------------------------------------
  Three basal feet (and  { One caudal and two lateral
    an apical horn).     {   feet,                     405. _Cortina_.

  Four basal feet (and   { Two sagittal and two
    an apical horn).     {   lateral feet,             406. _Stephanium_.



Subfamily 1. LITHOCIRCIDA, Haeckel.

_Definition_.--#Stephanida# without typical basal feet or cortinar feet.



Genus 401. _Archicircus_,[20] n. gen.

_Definition_.--#Stephanida# with a simple amphithect or diphragmatic ring,
smooth or thorny, without branched spines and basal feet.

The genus _Archicircus_ is the most primitive and simplest form of all
#Stephoidea#, and probably the common ancestral form, not only of this
suborder, but of the greater number of all NASSELLARIA (compare above, p.
893). The skeleton consists only of a quite simple sagittal ring, in which
commonly a slight difference of both poles of the main axis (basal and
apical pole) is visible, but no difference between the dorsal and the
ventral bow of the ring. In my Prodromus (1881, p. 447) the species of
_Archicircus_ were disposed partly in the subgenus _Monostephus_, partly in
the genus _Lithocircus_.



Subgenus 1. _Monostephus_, Haeckel, 1881, Prodromus, p. 447.

_Definition._--Ring circular, elliptical, or ovate, without prominent
corners.


1. _Archicircus princeps_, n. sp.

Gate circular. Ring circular, smooth, its transverse section also circular.
The simplest form of all #Stephoidea#.

_Dimensions._--Diameter of the gate 0.05 to 0.08; thickness of the ring
0.006 to 0.008.

_Habitat._--Central Pacific, Stations 265 to 274, depth 2350 to 2925
fathoms.


{941}2. _Archicircus monostephus_, n. sp. (Pl. 83, fig. 17).

Gate circular. Ring circular, with three elegantly denticulate edges (one
outer median and two lateral edges). Transverse section of the ring
triangular.

_Dimensions._--Diameter of the gate 0.06 to 0.08; thickness of the ring
0.01 to 0.008.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


3. _Archicircus ellipsis_, n. sp.

Gate elliptical. Ring elliptical, on the inner margin smooth, on the outer
margin with fifteen to twenty equal, short, simple, or slightly forked
thorns. Transverse section ovate.

_Dimensions._--Diameter of the gate 0.05 to 0.09; thickness of the ring
0.01 to 0.014.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms; also
fossil in Barbados.


4. _Archicircus ovalis_, n. sp.

Gate ovate. Ring elliptical, smooth, with three prominent, slightly
distorted edges, without thorns; in the transverse section triangular.

_Dimensions._--Diameter of the gate 0.08 to 0.12; thickness of the ring
0.006 to 0.009.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


5. _Archicircus monopylus_, n. sp.

Gate ovate. Ring ovate, thorny, with three distorted edges, in the
transverse section triangular; surface covered with numerous simple small
thorns arising from the three edges.

_Dimensions._--Diameter of the gate 0.1 to 0.15; thickness of the ring 0.01
to 0.012.

_Habitat._--Indian Ocean (Madagascar), Rabbe, surface.



Subgenus 2. _Archistephus_, Haeckel.

_Definition._--Ring polygonal, with four to six or more prominent corners
(and commonly with simple spines arising from the corners).


6. _Archicircus quadratus_, n. sp.

Gate square. Ring square, with three edges and four short simple pyramidal
spines on the four corners, opposite in pairs in two perpendicular
diameters. Transverse section triangular.

_Dimensions._--Diameter of the gate 0.08; thickness of the ring 0.008.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


{942}7. _Archicircus rhombus_, n. sp. (Pl. 81, fig. 7).

Gate rhombic. Ring rhombic, with four prominent edges and four pairs of
short, divergent, pyramidal spines on the four corners, arising from the
lateral edges of the four rods, about as long as the radius of the gate.

_Dimensions._--Diameter of the gate 0.04 to 0.08; thickness of the ring
0.007 to 0.01.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


8. _Archicircus duodenus_, n. sp.

Gate square or rhombic. Ring rhombic, with three prominent edges and twelve
stout and straight pyramidal spines, about as long as the radius of the
gate. In each of the four corners are three divergent spines, arising from
the three edges of each two meeting rods.

_Dimensions._--Diameter of the gate 0.08; thickness of the ring 0.012.

_Habitat._--North Atlantic, surface (Rabbe).


9. _Archicircus primordialis_, n. sp. (Pl. 81, fig. 1).

Gate ovate. Ring hexagonal, with three prominent edges and six short
pyramidal thorns at the six corners; the basal thorn is either simple or
forked.

_Dimensions._--Diameter of the gate 0.07; thickness of the ring 0.01 to
0.015.

_Habitat._--Central Pacific, Stations 265 to 274, depth 2350 to 2925
fathoms.


10. _Archicircus hexacanthus_, n. sp. (Pl. 81, fig. 4).

Gate subregular, hexagonal. Ring hexagonal, with three sharp edges and six
equal radial pyramidal spines, arising from the six corners and placed in
the plane of the ring, about as long as the diameter of the gate.

_Dimensions._--Diameter of the gate 0.05 to 0.07; thickness of the ring
0.01.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


11. _Archicircus hertwigii_, Haeckel.

  _Lithocircus annularis_, R. Hertwig (_non_ J. Müller), 1879, Organismus
  der Radiol., p. 69.     Taf. vii. fig. 5.

Gate hexagonal, with prolonged main axis. Ring hexagonal, with two
prominent edges and six pairs of equal, short, conical spines, arising from
the two edges of the six rods at the six corners and divergent on each side
of the plane of the ring. The basal spine-pair is doubled, therefore there
are in all fourteen spines.

_Dimensions._--Diameter of the gate 0.05 to 0.07; thickness of the ring
0.005 to 0.006.

_Habitat._--Mediterranean (Messina), Hertwig, surface.


{943}12. _Archicircus triglyphus_, n. sp.

Gate ovate. Ring hexagonal, with three prominent edges and twenty-two to
twenty-four simple curved spines, arising from the six corners and about as
long as the diameter of the gate. In the basal corner arise six to nine
larger spines, protecting the basal pole of the central capsule. From each
of the five other corners arise three spines, diverging from the three
edges.

_Dimensions._--Diameter of the gate 0.07 to 0.11; thickness of the ring
0.008 to 0.011.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


13. _Archicircus sexangularis_, n. sp. (Pl. 81, fig. 12).

Gate hexagonal or subcircular. Ring hexagonal, with two sharp prominent
edges and six pairs of divergent spines, about as long as the radius of the
gate, and arising from the two edges at the six corners. The two apical and
the two basal spines are simple and conical, whilst the eight other spines,
arising in pairs from the two dorsal and the two ventral corners, are
slightly forked.

_Dimensions._--Diameter of the gate 0.06 to 0.08; thickness of the ring
0.01 to 0.015.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.



Genus 402. _Lithocircus_,[21] J. Müller, 1856, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 484.

_Definition._--#Stephanida# with a simple amphithect or diphragmatic ring,
armed with branched spines, without typical basal feet.

The genus _Lithocircus_ is the oldest known form of all #Stephoidea#,
founded by J. Müller in 1856 for his _Lithocircus annularis_, the first
species of this suborder described. We retain here this cosmopolitan form
as the typical representative of the genus, which differs from the
preceding _Archicircus_, its ancestral form, in the development of branched
radial spines.


1. _Lithocircus annularis_, J. Müller.

  _Lithocircus annularis_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 29, Taf. i. fig. 1.

Gate circular. Ring circular, with four forked or simply branched spines,
opposite in pairs in two diameters, perpendicular one to the other. Spines
with slender curved fork-branches, about as long as the diameter of the
gate. The specimen figured by J. Müller bears a supernumerary fifth spine;
numerous other specimens observed by me exhibited a regular cross of four
spines.

_Dimensions._--Diameter of the gate 0.1 to 0.15; length of the spines 0.01
to 0.18.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific,
surface.


{944}2. _Lithocircus quadricornis_, n. sp. (Pl. 81, fig. 9).

Gate square. Ring square, with three sharp denticulate edges, and four
large bunches of richly branched spines on the four corners. In each corner
arise three curved spines, about as long as the diameter of the ring; their
numerous irregular branches are forked and curved like the antlers of deer.

_Dimensions._--Diameter of the gate 0.07; length of the horns 0.06 to 0.09.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


3. _Lithocircus decimalis_, n. sp. (Pl. 81, fig. 15).

Gate elliptical. Ring pentagonal, with three prominent edges and five pairs
of branched spines on the five corners. In each corner arise two or three
curved spines, about as long as the radius of the gate, each with two to
four forked branches.

_Dimensions._--Diameter of the gate 0.08; length of the spines 0.03 to
0.05.

_Habitat._--North Atlantic, Station 354, surface.


4. _Lithocircus hexablastus_, n. sp. (Pl. 81, fig. 17).

Gate elliptical. Ring hexagonal, with three prominent edges and six pairs
of branched spines, arising from the six corners. Each of the twelve spines
is short and stout, only half as long as the radius of the gate, and bears
a bunch of ten to twenty short, densely aggregated, conical or horn-like
curved branches.

_Dimensions._--Diameter of the gate 0.1; length of the spines 0.02 to 0.03.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


5. _Lithocircus crambessa_, n. sp. (Pl. 81, fig. 6).

Gate elliptical or subcircular. Ring hexagonal, with three wing-shaped
distorted edges and six groups of branched spines, arising from the six
corners. In each corner arise three short and stout divergent spines, each
bearing a bunch of numerous short roundish branches like a cauliflower,
scarcely as long as the thickness of the ring.

_Dimensions._--Diameter of the ring 0.1 to 0.12, length of the spines 0.01
to 0.02.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


6. _Lithocircus tarandus_, n. sp. (Pl. 92, fig. 19).

Gate circular. Ring hexagonal, with three sharp edges and six pairs of
large branched spines, arising from the flat lateral edges on the six
corners. Each of the twelve spines is horizontally expanded, longer than
the diameter of the ring and dichotomously forked like the antlers of a
{945}reindeer. If the lateral ends of the branches of this species become
united in the frontal plane, we get _Microcubus_, the four upper spines
forming the mitral ring, the four middle the equatorial ring, and the four
lower the basal ring.

_Dimensions_.--Diameter of the gate 0.08; length of the spines 0.09.

_Habitat_.--Central Pacific, Station 272, surface.


7. _Lithocircus furcatus_, n. sp.

Gate ovate. Ring ovate, with three sharp prominent edges. The two lateral
edges are smooth. The median edge (in the sagittal plane) bears sixteen to
twenty forked spines (commonly eight dorsal, eight ventral, and four
basal). All the spines are of nearly equal size, slightly curved, and about
half as long as the short sagittal axis of the ring.

_Dimensions_.--Diameter of the gate 0.08 to 0.12; length of the spines 0.03
to 0.04.

_Habitat_.--North Pacific, Station 253, depth 3125 fathoms.


8. _Lithocircus magnificus_, n. sp. (Pl. 81, fig. 16).

Gate ovate or nearly elliptical. Ring ovate, with three prominent edges,
and numerous richly branched spines arising from the three edges. The
specimen figured, which I observed living in the Mediterranean, exhibited
eight bunches of larger spines, three dorsal, three ventral, one apical,
and one basal bunch; the latter much larger than the seven others. Each
bunch was composed of two to four larger and numerous smaller spines, their
branches curved and forked. The ovate purple central capsule, with a
distinct podoconus, filled more than the half of the gate.

_Dimensions_.--Diameter of the gate 0.1 to 0.13; length of the spines 0.05
to 0.15.

_Habitat_.--Mediterranean (Portofino, 1880), Atlantic (Canary Islands),
Station 354, surface.



Genus 403. _Zygocircus_,[22] Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
xxxvi. p. 496.

_Definition_.--#Stephanida# with a simple dipleuric or bilateral ring,
smooth or thorny, without branched spines and basal feet.

The genus _Zygocircus_ and the following _Dendrocircus_ differ from the two
preceding older genera in the bilaterally symmetrical or dipleuric form of
the sagittal ring. Whilst in _Archicircus_ and _Lithocircus_ the two
sagittal halves or bows of the ring, the dorsal and ventral bow, are equal
(therefore the fundamental form amphithect or diphragmatic), here both bows
become distinctly different; the dorsal bow is constantly more straight
(often vertical), the ventral bow more convex (obliquely ascending). This
dipleuric differentiation is most important, as it is transmitted to the
greater number of NASSELLARIA by heredity.


{946}1. _Zygocircus sagittalis_, n. sp.

Gate ovate. Ring half ovate or nearly triangular, with three curved edges
and three prominent corners, one apical and two basal protuberances. Dorsal
rod vertical, twice as long as the horizontal basal rod. Ventral rod
convexly curved.

_Dimensions._--Diameter of the gate 0.05 to 0.07; height of the tubercles
0.01 to 0.015.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2900 fathoms.


2. _Zygocircus trigonus_, n. sp.

Gate triangular. Ring triangular, with three curved edges and three
prominent corners, which are prolonged into nine divergent conical spines;
three spines arising from the three edges of each corner. Dorsal rod
vertical; ventral and basal rods curved and convergent.

_Dimensions._--Diameter of the gate 0.11 to 0.13; length of the spines 0.01
to 0.015.

_Habitat._--Indian Ocean, Sunda Archipelago (Rabbe), surface.


3. _Zygocircus tetragonus_, n. sp.

Gate ovate. Ring quadrangular, without edges, with four simple conical
spines of different sizes; one smaller apical, one larger basal, and two
equatorial spines of middle size (one dorsal and one ventral). Dorsal and
ventral rod curved.

_Dimensions._--Diameter of the gate 0.04 to 0.06; length of the spines
0.018 to 0.026.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.


4. _Zygocircus rhombicus_, n. sp.

Gate rhombic. Ring rhombic, with three prominent edges, and eight short
conical curved spines arising from the lateral edges at the four corners of
the rhombus. The basal and ventral spine are larger than the apical and
dorsal spine; the ventral rod is more curved (with smaller angle) than the
shorter dorsal rod. The medial edge of the ring is smooth, without spines.

_Dimensions._--Diameter of the gate 0.08; length of spines 0.02 to 0.04.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.


5. _Zygocircus pentagonus_, n. sp. (Pl. 81, fig. 8).

Gate roundish pentagonal. Ring very thick (about as thick as the radius of
the gate), irregularly pentagonal, with prominent sagittal edge. On both
sides of the latter arise at the five corners five pairs of short simple
irregularly curved spines. The four ventral spines are larger than the four
dorsal, and the two basal spines larger than the eight former, forked. (In
fig. 8 the basal spines are turned upwards.)

_Dimensions._--Diameter of the gate 0.07; length of the spines 0.04 to
0.06.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


{947}6. _Zygocircus hexagonus_, n. sp.

Gate irregularly hexagonal. Ring obliquely hexagonal, thick, without edges,
with six short and stout conical spines on the six corners. The two spines
of the curved ventral rod are longer than the two spines of the straight
dorsal rod. The apical spine is smaller and the basal spine larger than the
four others.

_Dimensions_.--Diameter of the gate 0.07 to 0.09; length of the spines 0.01
to 0.03.

_Habitat_.--North Pacific, Station 241, depth 2300 fathoms.


7. _Zygocircus triquetrus_, n. sp. (Pl. 81, fig. 3).

Gate obliquely ovate. Ring obliquely hexagonal, with three sharp edges and
three short conical spines on each of the six corners. Therefore each
hexagonal edge bears six short radial spines of equal size.

_Dimensions_.--Diameter of the gate 0.04 to 0.08; length of the spines 0.01
to 0.02.

_Habitat_.--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.


8. _Zygocircus dodecanthus_, n. sp.

Gate semicircular. Ring semicircular or irregularly hexagonal, without
edges, with twelve short blunt spines, arising in pairs from the six
corners; two apical, two basal, and between them two equatorial corners.
Three pairs of spines remain on the straight dorsal rod, three on the
curved ventral rod.

_Dimensions_.--Diameter of the gate 0.04 to 0.06; length of the spines 0.01
to 0.02.

_Habitat_.--Central Pacific, Stations 263 to 268; depth 2650 to 2900
fathoms.


9. _Zygocircus acacia_, n. sp. (Pl. 81, fig. 5).

Gate obliquely ovate. Ring semi-ovate, with straight dorsal and curved
ventral rod, partly with distorted edges. Six bunches of numerous short and
straight conical spines arise from the ring, one larger bunch (often
trifid) from the apex, two smaller bunches from the dorsal, two from the
ventral rod, and one very large bunch from the base. The six bunches are
often more separated, smaller, and the spines shorter than in the figured
specimen, which passes over into _Dendrocircus_.

_Dimensions_.--Diameter of the gate 0.12 to 0.16; length of the spines,
0.01 to 0.07.

_Habitat_.--Central Pacific, Station 266, depth 2750 fathoms.


10. _Zygocircus polygonus_, n. sp. (Pl. 81, fig. 2).

Gate irregularly roundish or ovate. Ring irregularly polygonal or sometimes
nearly circular, without edges, armed with a single series of ten to
fifteen short pyramidal spines, which are irregularly {948}disposed in the
sagittal plane. The ventral rod is strongly curved, often semicircular, the
dorsal rod less curved or nearly straight.

_Dimensions_.--Diameter of the gate 0.05 to 0.07; length of the spines
0.004 to 0.02.

_Habitat_.--Cosmopolitan--Atlantic, Pacific; also fossil in Barbados.


11. _Zygocircus bütschlii_, n. sp.

  _Zygocircus productus_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. p. 497.

Gate obliquely ovate. Ring irregularly roundish, semi-ovate or ovate, with
interrupted and distorted edges, and with a large number (ten to twenty or
more) of simple, irregularly formed and asymmetrically disposed spines;
commonly some larger spines at the base.

_Dimensions_.--Diameter of the gate 0.05 to 0.09; length of the spines
0.005 to 0.02.

_Habitat_.--Fossil in Barbados.


12. _Zygocircus productus_, Bütschli.

  _Zygocircus productus_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi p. 496.

  _Lithocircus productus_, R. Hertwig, 1879, Organismus d. Radiol., p. 69,
  Taf. vii. fig. 4.

Gate obliquely ovate. Ring obliquely ovate, with three complete prominent
edges and with numerous (ten to twenty or more) simple, short conical
spines, arising in three series from the three edges; commonly some smaller
spines at the base.

_Dimensions_.--Diameter of the gate 0.1 to 0.2; length of the spines 0.005
to 0.02.

_Habitat_.--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.



Genus 404. _Dendrocircus_,[23] Haeckel, 1881, Prodromus, p. 447.

_Definition_.--#Stephanida# with a simple dipleuric or bilateral ring,
armed with branched spines, without typical basal feet.

The genus _Dendrocircus_ has the same dipleuric or bilaterally symmetrical
form of the sagittal ring as its ancestral genus _Zygocircus_. It differs
from the latter in the development of branched radial spines, and therefore
bears to it the same relation as the amphithect _Lithocircus_ does to the
simpler _Archicircus_.


1. _Dendrocircus quadrangulus_, n. sp.

Gate irregularly quadrangular or nearly semicircular. Ring quadrangular,
edgeless, with four unequal sides; ventral rod more curved and with longer
sides than the dorsal rod. From the four edges arise four strong,
irregularly branched spines, about as long as the diameter of the gate,
{949}with curved branches; the ventral and basal spines larger than the
dorsal and apical spines. Similar to _Lithocircus quadricornis_ (Pl. 81,
fig. 9), but less branched, and with a striking difference between the
shorter dorsal and the longer ventral rod.

_Dimensions._--Diameter of the gate 0.04 to 0.06; length of the spines 0.05
to 0.07.

_Habitat._--North Pacific, Station 256, depth 2950 fathoms.


2. _Dendrocircus dodecarrhiza_, n. sp.

Gate obliquely ovate. Ring irregularly quadrangular, with three prominent
edges. From the latter arise at the four corners twelve divergent,
irregularly branched spines (three in each corner), about as long as the
radius of the gate, with curved branches; the three basal spines larger
than the nine others.

_Dimensions._--Diameter of the gate 0.08 to 0.1; length of the spines 0.04
to 0.06.

_Habitat._--Indian Ocean (Maldive Islands), surface (Haeckel).


3. _Dendrocircus dodecancistra_, n. sp. (Pl. 81, fig. 11).

Gate obliquely ovate or nearly elliptical. Ring irregularly ovate, with
three distorted edges and six pairs of branched spines. The two ventral
pairs are much more distant than the two dorsal pairs, the ventral rod
being longer and more curved than the dorsal rod. All twelve spines are of
nearly equal size, are more or less curved, about as long as the diameter
of the gate, and each bears six to twelve irregular short branches at the
end.

_Dimensions._--Diameter of the gate 0.07 to 0.08; length of the spines 0.05
to 0.08.

_Habitat._--Tropical Atlantic, Station 342, depth 1445 fathoms.


4. _Dendrocircus arborescens_, n. sp. (Pl. 81, fig. 10).

Gate irregularly roundish or nearly circular. Ring of the same form, with
slight edges and six pairs of elegant arborescent spines (one apical, two
dorsal, two ventral, and one basal pair); the three latter somewhat larger
than the three former. Each tree is larger than the ring, in the basal half
simple, in the distal half forked, each fork-branch with numerous
dichotomous terminal branches.

_Dimensions._--Diameter of the gate 0.06 to 0.08; length of the spines 0.12
to 0.15.

_Habitat._--Central Pacific, Stations 266 to 274, surface.


5. _Dendrocircus elegans_, n. sp. (Pl. 81, fig. 13).

Gate irregularly ovate. Ring thick, ovate, with three denticulate edges and
six bunches of stout, branched and spinulate, curved spines. The four
ventral spines are more distant than the four dorsal, the ventral rod being
more curved than the dorsal. The latter bears above the two apical spines.
The two basal spines are much larger, deeply forked; their four
fork-branches may be compared to the four basal feet of _Stephanium_.

_Dimensions._--Diameter of the ring 0.09 to 0.11; length of the spines 0.03
to 0.06.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


{950}6. _Dendrocircus barbadensis_, n. sp.

Gate irregularly ovate or nearly semicircular. Ring of the same oblique
form, thick, with interrupted and distorted edges, armed with eight to
twelve larger irregularly formed and branched acute spines; between them
numerous conical smaller spines. This common species is very polymorphous
and variable.

_Dimensions._--Diameter of the ring 0.05 to 0.08; length of the spines
0.005 to 0.02.

_Habitat._--Fossil in Barbados.


7. _Dendrocircus stalactites_, n. sp. (Pl. 81, fig. 14).

Gate obliquely ovate. Ring irregularly ovate or roundish, very thick,
without edges, armed with numerous (eight to twelve or more) short and
stout branches, which are shorter than the diameter of the gate,
irregularly disposed and branched, with very numerous clustered blunt
ramules.

_Dimensions._--Diameter of the gate 0.07 to 0.09; length of the spines 0.02
to 0.06.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



Subfamily 2. CORTINIDA, Haeckel.

_Definition._--#Stephanida# with typical basal feet (or cortinar feet).



Genus 405. _Cortina_,[24] n. gen.

_Definition._--#Stephanida# with a simple dipleuric or bilateral ring,
bearing at the base three divergent feet (one odd caudal and two paired
lateral feet).

The genus _Cortina_ and the following _Stephanium_ represent together the
small but very important group of Cortinida, differing from the simple
Lithocircida in the possession of three typical basal feet, which are
transmitted to the majority of the NASSELLARIA by heredity, and produce
their peculiar triradial structure. They appear therefore as a combination
of the simple ring (_Zygocircus_) with three basal feet (_Plagonium_). One
of these three divergent feet is the odd caudal foot, opposite to the
apical horn; the two others are the paired lateral or pectoral feet. (On
the probable origin and the typical signification of _Cortina_ compare
above, pp. 891-894.)


1. _Cortina tripus_, n. sp. (Pl. 83, fig. 9).

Ring ovate, smooth, or with a few short thorns. Apical horn oblique,
curved, simple, smooth, about as long as the sagittal axis of the ring.
Feet divergent, curved, simple, smooth, about as {951}long as the horn; the
caudal foot shorter than the two pectoral feet. Very variable in form and
size.

_Dimensions._--Height of the ring 0.06 to 0.09, breadth 0.04 to 0.06;
length of the feet 0.05 to 0.1.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface and in various
depths.


2. _Cortina typus_, n. sp. (Pl. 97, fig. 1).

Ring kidney-shaped or nearly semicircular, with revolute vertical dorsal
rod and strongly curved ventral rod; both rods with two pairs of
spine-bunches. Apical horn nearly straight, thorny, longer than the ring,
directed a little obliquely backwards. Feet slightly curved, of equal
length, two to three times as long as the ring; each armed with few large
bunches of curved spines, which are more developed in the caudal foot than
in the two pectoral feet.

_Dimensions._--Height of the ring 0.14, breadth 0.08; length of the feet
0.2 to 0.3.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


3. _Cortina conifera_, n. sp.

Ring subcircular, smooth. Apical horn and the three divergent feet of equal
size and similar form, cylindrical, straight, about as long as the ring, at
the distal end thickened, with a dimply cone (similar to _Tripospyris
conifera_ and _Tripospyris eucolpa_, Pl. 84, figs. 4, 7).

_Dimensions._--Height of the ring 0.08, breadth 0.06; length of the feet
0.09.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


4. _Cortina furcata_, n. sp.

Ring elliptical, with three forked horizontal spines (one on the dorsal and
two on the ventral rod). Apical horn and the three divergent feet of equal
size, somewhat longer than the ring, slightly curved, in the distal half
forked.

_Dimensions._--Height of the ring 0.07, breadth 0.05; length of the feet
0.09.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms. Fossil in
Barbados.


5. _Cortina dendroides_, n. sp.

Ring ovate, with six pairs of branched horizontal spines, three on the
dorsal and three on the ventral rod. Apical horn very large, arborescent,
about as long and as broad as the ring. Feet similar to the horn, also
richly branched, of equal size. All the rods and their branches curved,
with prominent distorted edges.

_Dimensions._--Height of the ring 0.13 to 0.17, breadth 0.1 to 0.12; length
of the feet 0.15 to 0.2.

_Habitat._--Central Pacific, Stations 266 to 274, depth 2350 to 2925
fathoms.


{952}6. _Cortina cervina_, n. sp. (Pl. 92, fig. 21).

Ring ovate, with four pairs of forked horizontal spines (two dorsal and two
ventral pairs). Apical horn straight and stout, as long as the ring, with
trifid point. Three feet equal, widely divergent, very large, branched like
a deer's antler, with very numerous short and stout, curved and pointed
branches. All rods and branches roundish, without edges.

_Dimensions._--Height of the ring 0.1, breadth 0.07; length of the feet
0.12 to 0.16.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.



Genus 406. _Stephanium_,[25] n. gen.

_Definition._--#Stephanida# with a simple dipleuric or bilateral ring,
bearing at the base four divergent feet (two sagittal and two lateral
feet).

The genus _Stephanium_ differs from the preceding nearly allied _Cortina_
in the production of four basal feet; the new foot, missing in the latter,
is the anterior or sternal foot. Therefore _Stephanium_ may be regarded as
the archetype of all those NASSELLARIA in which, on the base of the
sagittal ring, there are developed four typical feet--two sagittal feet
(the posterior caudal and anterior sternal foot) and two lateral feet
(right and left). On the origin of _Stephanium_ compare above, p. 893, &c.


1. _Stephanium quadrupes_, n. sp. (Pl. 92, fig. 20).

Ring ovate, with three prominent dentate edges and a short pyramidal apical
horn. Four feet all of nearly equal size, about as long as the ring, also
with three thorny edges, in the upper half divergent, in the lower
convergent.

_Dimensions._--Height of the ring 0.12, breadth 0.08; length of the feet
0.11 to 0.13.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Stephanium tetrapus_, n. sp.

Ring elliptical, without edges, thorny, with a stout, thorny apical horn of
the same length. Four feet curved and irregularly branched, divergent, of
different size. The two sagittal feet (the anterior sternal and posterior
caudal) about as long as the ring. The two lateral feet (right and left)
nearly twice as long, more richly branched.

_Dimensions._--Height of the ring 0.16, breadth 0.11; length of the feet
0.15 to 0.3.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms. Fossil in
Barbados.



{953}Family XLIX. #SEMANTIDA#, n. fam.

_Definition._--#Stephoidea# with a single vertical ring (the primary
sagittal ring), bearing on its base a horizontal ring (basal or cortinar
ring) with two to four or more basal gates (or cortinar pores).

The family #Semantida# differs from the preceding Stephanida in the
development of a small horizontal ring on the base of the primary vertical
sagittal ring. By the crossing of these two rings a small latticed basal
plate is formed, with one or two pairs of pores; rarely with a greater
number of "basal pores." The production of this characteristic "basal
plate" is of the greatest morphological importance, as the beginning of the
numerous different lattice-formations, which are differentiated in the
great majority of NASSELLARIA.

In my Prodromus (1881, p. 446) I had enumerated the Semantida with three
genera (Nos. 298 to 300) as a separate subfamily of the Dyostephida or
"Stephoidea biannularia," and characterised these "Dyostephanida" by the
following definition: "Skeleto annulis duobus composito, qui in duobus
planis invicem perpendicularibus jacent; altero annulo (sagittali)
verticali, altero (basali) horizontali." As the names there given were
already employed with another signification, and as the Zygostephanida
(there united with the Dyostephanida) are more closely related to the
Coronida, I now change the names, and propose to call the family Semantida,
expressing by this term the typical similarity of the skeleton to a
signet-ring (_Semantis_, _Semantrum_, _Semantidium_).

At about the same time, some #Stephoidea# of this family were accurately
described by Bütschli (1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 495,
Taf. xxxii. figs. 6, 7, 8). He called them _Stephanolithis_, a name which
Ehrenberg had employed, not for complete shells of Radiolaria, but for
isolated parts of such, and for siliceous fragments of different skeletons,
needles of Sponges, &c. The three species described by Bütschli represent
three different genera of our Semantida, viz., _Semantis spinescens_ (with
two gates in the basal plate), _Semantrum mülleri_ (with four gates), and
_Semantidium haeckelii_ (with six gates). He pointed out the great
morphological value of the fenestrated basal plate and its paired gates, as
beginnings of numerous other NASSELLARIA. But his opinion, that in all
#Spyroidea# and #Cyrtoidea#, derived from these, two pairs of basal gates
were constant, was erroneous, nor was the formation of the first pair
naturally explained; he supposed that the formation of the basal plate
begins by development of an odd sagittal apophysis, arising from the base
of the primary sagittal ring. But this odd sagittal apophysis ("der unpaare
mediane Kieselfortsatz c1", _loc. cit._, p. 497) is in reality not a
primary {954}and essential part of the skeleton, but secondary and of
little morphological value, absent in the majority of the Semantida and of
the other NASSELLARIA.

We divide our family Semantida into two different subfamilies, which
possibly possess a direct phylogenetic relation to the two subfamilies of
Stephanida:--The Semantiscida have no typical feet, and have arisen
directly from the Lithocircida; the Cortiniscida, however, possess the
three typical basal feet of _Cortina_, and may therefore be derived
directly from the Cortinida. Since these three cortinar feet are probably
identical with the three primary radial rods of the #Plectoidea#, an
immediate affinity also to these NASSELLARIA is indicated.

The Semantiscida, which do not possess these three basal cortinar feet, are
the simpler forms of the family. The simplest of all, and perhaps the
common ancestral form of the whole family, is _Semantis_ (Pl. 92, figs. 1,
2). It may be derived from _Archicircus_ or _Zygocircus_ by development of
two pairs of horizontal apophyses on its base, around the porochora of the
central capsule. The two rods of each side (right and left), becoming
curved one towards the other, and meeting laterally, form a simple
horizontal gate, and the two paired basal gates together, a horizontal ring
or basal ring, to which the primary sagittal ring is perpendicular. In the
next allied genus, _Semantrum_ (Pl. 92, figs. 3-5), three pairs of
horizontal apophyses are developed, and therefore two pairs of basal gates
produced, an anterior and a posterior. In the third genus, _Semantidium_
(Pl. 92, figs. 6, 7), three pairs of basal pores or gates are visible,
surrounded and separated by four pairs of horizontal apophyses, which arise
from the base of the sagittal ring. Finally, in _Clathrocircus_ (Pl. 92,
figs. 8-10) the number of apophyses is much increased, and two parallel
rows of pores are developed along the two sides of the sagittal ring.

The basal plate or the "seal," developed from the base of the primary
sagittal ring or "signet-ring," is therefore a horizontal ring, which
becomes bisected by the latter, and exhibits either one pair of primary
"basal gates" or two or three pairs of these important basal pores, rarely
more. Since these pores possess the greatest morphological value, and are
probably everywhere homologous, we give to them and to the separating
apophyses certain names, and call the anterior pair of gates, "jugular
pores" (_i_ in our figures, the pair I of Bütschli); the middle (usually
the largest) pair, "cardinal pores" (_k_ in our figures, the pair II of
Bütschli), and the posterior, smaller pair, "cervical pores," _l_. The
typical pairs of rods, by the union of which these basal pores arise, are
the following:--(1) the clavicular or furcular rods, _f_, the first pair
(rods _e_1 of Bütschli), (2) the coracal rods, _e_, between the jugular and
cardinal pores (rods _e_ of Bütschli), (3) the scapular rods, _g_, between
the cardinal and cervical pores (rods _e_2 of Bütschli), (4) the cervical
rods, the fourth pair of apophyses, the most posterior, _h_. Bütschli
supposes that the topographical succession of the three typical pairs of
basal pores is also the chronological succession, the jugular being formed
first, the {955}cardinal second and the cervical pores third but it seems
that this succession is often altered and that the cardinal pores (the
largest), appear first, the jugular pores (in front of them) second and the
cervical pores third (or perhaps sometimes in the inverse succession).

The Cortiniscida, the second subfamily of Semantida, differ from the
preceding Semantiscida in the possession of three typical basal feet, which
are probably inherited from the Cortinida, and perhaps indirectly from the
Plagonida (_Plagoniscus_). The simplest and the most important form of this
second family is _Cortiniscus_ (Pl. 92, figs. 11-13), differing from its
probable ancestral form, _Cortina_, in the development of a basal ring,
produced by horizontal union of the basal apophyses. The three typical feet
are the same as in all triradiate NASSELLARIA, two paired pectoral feet
(_p__{1}, _p__{11}) diverging on the anterior base of the sagittal ring,
whilst the odd caudal foot (_c_) lies on its posterior base in the sagittal
plane and appears as a basal prolongation of the dorsal rod of the sagittal
ring; the upper part of the dorsal rod is usually prolonged into an
ascending apical horn. In _Stephaniscus_ (Pl. 92, figs. 14, 15) four basal
feet are visible, an anterior or sternal foot (_z_) being added as a
prolongation of the basal rod of the ring, opposite to the caudal foot.
Finally, _Semantiscus_ (Pl. 92, figs. 16-18) is distinguished by the
possession of six divergent basal feet, probably identical with those of
all six-radiate NASSELLARIA; three of these may be regarded as primary and
perradial, the odd caudal and the paired pectoral feet; the three other
intercalated as secondary or interradial feet, the odd sternal (_z_) and
the paired tergal feet (_t__{1}, _t__{11}).

The basal plate of these Cortiniscida exhibits the same important
differences as in the preceding Semantiscida, either one, or two, or three
pairs of basal gates being developed. But there occur also in some species
(mainly in _Cortiniscus_) only three basal gates, an odd anterior (between
the two pectoral feet and a connecting horizontal bar), and two paired
posterior (between the two pectoral and the odd caudal foot). It requires
further accurate researches to solve the important problem, what the true
homologies of these typical basal pores and the separating bars are in the
different genera of Semantida. In _Semantiscus_ there are three pairs of
basal pores in the horizontal seal, corresponding to those of _Semantidium_
and the radial rods or bars between, these are the basal parts of the six
radial feet; therefore the odd caudal foot (_t_) seems to be the posterior,
and the odd sternal foot (_z_) the anterior prolongation of the basal part
of the primary sagittal ring; the two paired anterior or pectoral feet
(_p__{1}, _p__{11}) the prolongations of the coracal rods (_e_) and the two
paired posterior or tergal feet (_t__{1}, _t__{11}), the prolongations of
the scapular rods (_g_). But it is not yet certain whether these six radial
feet and the separating gates of the basal plate are all the same and truly
homologous in all six-radiate NASSELLARIA. In every case the comparative
study of the Semantida is of the highest value for the accurate knowledge
of the MONOPYLEA.

{956}_Synopsis of the Genera of Semantida._

  -------------------------------------------------------------------------
  I. Subfamily Semantiscida.
     Basal ring without typical, regularly disposed basal feet
       (no cortinar feet).
  -------------------------------------------------------------------------
                           { Two basal pores,         407. _Semantis_.
  Only two, four, or six   {
    basal pores (no dorsal { Four basal pores,        408. _Semantrum_.
    and ventral pores).    {
                           { Six basal pores,         409. _Semantidium_.

  Besides four basal pores, also apical pores or
    dorsal and ventral pores along the whole ring,    410. _Clathrocircus_.
  -------------------------------------------------------------------------
  II. Subfamily Cortiniscida.
      Basal ring with typical, regularly disposed basal feet
         (cortinar feet).
  -------------------------------------------------------------------------
                           { One odd caudal foot and
  Three basal feet.        {   two paired lateral
                           {   feet,                  411. _Cortiniscus_.

                           { Two sagittal and two
  Four basal feet.         {   lateral or pectoral
                           {   feet,                  412. _Stephaniscus_.

                           { Two sagittal, two
  Six basal feet.          {   pectoral, and two
                           {   tergal feet,           413. _Semantiscus_.



Subfamily 1. SEMANTISCIDA, Haeckel.

_Definition._--#Semantida# without typical basal feet or cortinar feet.



Genus 407. _Semantis_,[26] n. gen.

_Definition._--#Semantida# with two basal pores (or jugular pores), without
typical basal feet.

The genus _Semantis_, the most primitive and the oldest of the Semantida,
is of the greatest morphological interest, as the first form of
#Stephoidea# which produces gates or pores by communicating branches, and
therefore the probable ancestral form not only of this family, but of the
greater number of all #Stephoidea#, and perhaps even of all #Spyroidea# and
#Cyrtoidea#. _Semantis_ arises from _Archicircus_ by the production of two
pairs of lateral branches from the basilar rod of the sagittal ring, one
anterior pair of clavicular rods, and one posterior pair of coracal rods.
By junction of the clavicular and coracal rod on each side arises a left
and a right pore, the "jugular pore or jugular gate."


1. _Semantis biforis_, n. sp. (Pl. 92, fig. 2).

Sagittal ring obliquely ovate, nearly trapezoidal, with six pairs of short
mammillated knobs or branches; dorsal rod straight, vertical, with two
pairs of knobs, ventral rod strongly convex, also with {957}two pairs of
knobs; two other pairs in the apical rod. Basilar rod horizontal, straight.
Basal ring with six pairs of similar knobs, three on each side. Basal gates
ovate or nearly triangular.

_Dimensions._--Height of the sagittal ring 0.09, breadth 0.07.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


2. _Semantis distoma_, n. sp.

Sagittal and basal ring nearly of the same form as in the preceding
species, but half as thick and armed with numerous branched spines which
are about half as long as the diameter of the main gate, and with thin and
curved pointed branches.

_Dimensions._--Height of the sagittal ring 0.11, breadth 0.08.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


3. _Semantis dipyla_, n. sp.

Sagittal ring kidney-shaped, very thick, with six pairs of short, thorny,
or irregularly tuberculated knobs (two dorsal, two apical, and two ventral
pairs). Basal ring smooth, scarcely half as thick, horizontal, with two
semicircular basal gates, about half as broad as the main gate. From the
two opposite lateral corners of the basal ring two slender upwardly curved
spines arise, resembling the basal part of a commencing frontal ring.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.05.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


4. _Semantis sigillum_, n. sp. (Pl. 92, fig. 1).

Sagittal ring elliptical, with four pairs of stout arborescent spines (two
apical and two equatorial pairs), which are irregularly branched and
forked, with numerous thin lateral branches. Apex with a short conical
trifid vertical horn. Basal ring thorny, with obliquely descending slightly
curved bars.

_Dimensions._--Height of the sagittal ring 0.12, breadth 0.09.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


5. _Semantis distephanus_, n. sp. (Pl. 83, fig. 3).

Sagittal ring thin, semicircular, smaller than the thin basal ring, which
exhibits two semicircular gates. Both rings are armed with numerous small
spines of equal size, which on the former are arranged in two, on the
latter in three regular rows. (The basal rod of the sagittal ring,
separating the two basal gates, in fig. 3 is, by mistake, not distinctly
enough drawn.)

_Dimensions._--Height of the sagittal ring 0.06, breadth 0.08.

_Habitat._--Tropical Atlantic, Station 348, surface.


{958}6. _Semantis spinescens_, Haeckel.

  _Stephanolithis spinescens_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p.160, Taf. i. fig. 29.

  _Stephanolithis spinescens_, Bütschli, 1882, Zeitschr. f. wiss. Zool.,
  vol. xxxvi. p. 497, Taf. xxxii. figs. 7_a_, 7_b_.

Sagittal ring ovate with four pairs of thin, irregularly branched spines,
two apical pairs, one on the straight dorsal rod and one on the curved
ventral rod. Basilar rod with a posterior and an anterior forked rod
(commencing caudal and sternal foot). Basal ring square, with two lateral
spines, and two triangular gates scarcely one-third as broad as the
ring-gate. An internal ascending procolumna (rod _c__1 in the figure of
Bütschli) connects the basal and ventral rods of the sagittal ring.

_Dimensions._--Height of the sagittal ring 0.1, breadth 0.07.

_Habitat._--Fossil in Barbados.



Genus 408. _Semantrum_,[27] n. gen.

_Definition._--#Semantida# with four basal pores (two anterior jugular and
two posterior cardinal pores), without typical basal feet.

The genus _Semantrum_, one of the most important of the NASSELLARIA, arises
from the preceding _Semantis_ by duplication of the two basal gates. Behind
the pair of coracal rods there arises from the basilar rod of the sagittal
ring a third pair of lateral horizontal branches, the scapular rods. These
become connected with the coracal rods on each side, and so produce a
second posterior pair of basal pores, the "cardinal gates." These are
constantly larger than the anterior "jugular gates." Therefore the vertical
ring of _Semantrum_ possesses a horizontal basal ring with four very
characteristic gates, enclosed by three pairs of lateral curved and
connected branches, and these become transmitted by heredity to the
majority of the NASSELLARIA.


1. _Semantrum quadrifore_, n. sp. (Pl. 92, fig. 5).

Sagittal ring subcircular or ovate, with three edges and four sagittal
forked spines on the odd edge (two dorsal and two ventral spines). Basal
ring decagonal, with ten simple or forked spines on the ten corners.
Jugular gates tetragonal. Cardinal gates pentagonal.

_Dimensions._--Height of the sagittal ring 0.09, breadth 0.07.

_Habitat._--Tropical Atlantic, Station 351, surface.


{959}2. _Semantrum tetrastoma_, n. sp. (Pl. 92, fig. 3).

Sagittal ring semicircular, thorny, without edges. Basal ring tetragonal or
nearly cordate, with a small anterior and a large posterior bow-shaped
incision; on the lateral edges with numerous irregular thorns. Jugular
gates pear-shaped. Cardinal gates nearly kidney-shaped.

_Dimensions._--Height of the sagittal ring 0.1 to 0.14, breadth 0.07 to
0.09.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


3. _Semantrum tetrapylum_, n. sp.

Sagittal ring elliptical, tuberculate. Basal ring trapezoidal, also with
roundish thick rods and small irregular tubercles on the margin. Jugular
gates ovate, two-thirds as broad as the triangular cardinal gates.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.05.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.


4. _Semantrum mülleri_, Haeckel.

  _Stephanolithis mülleri_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi pp. 499, 539, Taf. xxxii. figs. 8_a_, 8_b_, 8_c_.

Sagittal ring nearly semicircular or obliquely ovate, thorny. Basal ring
also nearly semicircular, with two slight sagittal incisions (one anterior
and one posterior), on the lateral edges with numerous small thorns.
Jugular pores (pair I of Bütschli) pear-shaped. Cardinal pores (pair II of
Bütschli) triangular. Sometimes (but not constantly) a pair of cervical
bows connects the scapular bars with the subvertical dorsal rod of the
sagittal ring.

_Dimensions._--Height of the sagittal ring 0.09, breadth 0.06.

_Habitat._--Fossil in Barbados.


5. _Semantrum sphragisma_, n. sp.

Sagittal ring circular, smooth. Basal ring also nearly circular and smooth;
its four basal gates of nearly equal size, elliptical or subcircular; the
jugular pores scarcely smaller than the cardinal pores. All rods smooth,
cylindrical, without edges and thorns.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.07.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms; also fossil
in Barbados.


6. _Semantrum bütschlii_, n. sp.

Sagittal ring triangular, with vertical straight ascending dorsal rod,
horizontal straight basilar rod and obliquely ascending, slightly curved
ventral rod; all rods nearly cylindrical, with irregular {960}branched
thorns and distorted edges. Jugular pores triangular, scarcely half as
broad as the large semicircular cardinal pores.

_Dimensions._--Height of the sagittal ring 0.11, breadth 0.08.

_Habitat._--Fossil in Barbados.


7. _Semantrum signarium_, n. sp. (Pl. 92, fig. 4).

Sagittal ring obliquely ovate, thorny. Basal ring kidney-shaped or nearly
pentagonal, with broad concave dorsal incision and five larger branched
spines on the five corners; between them smaller thorns. Jugular gates
pear-shaped, scarcely half as broad as the triangular cardinal gates.

_Dimensions._--Height of the sagittal ring 0.12, breadth 0.09.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 409. _Semantidium_,[28]  n. gen.

_Definition._--#Semantida# with six basal pores (two anterior jugular, two
middle cardinal, and two posterior cervical pores), without typical basal
feet.

The genus _Semantidium_ exhibits a further developmental stage of the basal
plate of the Semantida. Whilst this plate in _Semantis_ possesses one pair
of basal pores, and in _Semantrum_ two pairs, here in _Semantidium_ it has
three pairs. The new third pair is produced on the dorsal edge of the basal
plate, which becomes connected with the basal part of the dorsal rod of the
sagittal ring by a pair of cervical rods. The middle pair of pores (the
cardinal) are always larger than the anterior (jugular) and the posterior
(cervical pores). The same form of basal plate is preserved in numerous
#Spyroidea# and #Cyrtoidea#, as a "cortinar septum with six collar pores,"
(_e.g._, Pl. 53, fig. 18).


1. _Semantidium hexastoma_, n. sp. (Pl. 92, fig. 6).

Sagittal ring ovate, thorny. Basal ring rhombic or nearly square, with four
short conical descending spines on the four prominent edges (two sagittal
and two lateral); between them numerous smaller irregular thorns. Jugular
and cervical gates nearly equal, ovate, half as broad as the triangular
cardinal gates between them.

_Dimensions._--Height of the sagittal ring 0.14, breadth 0.1.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


2. _Semantidium sexangulum_, n. sp.

Sagittal ring ovate, with six pairs of short branched thorns (two apical,
two dorsal, and two ventral). Basal ring hexagonal, with three pairs of
short branched thorns on the six corners (one {961}sagittal pair, one
posterior and one anterior). All six gates of the basal plate triangular,
the jugular and cervical a little smaller than the cardinal gates.

_Dimensions._--Height of the sagittal ring 0.1, breadth 0.07.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


3. _Semantidium haeckelii_, Bütschli.

  Stephanolithis Haeckelii, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. pp. 499, 538, Taf. xxxii. figs. 6_a_, 6_b_.

Sagittal ring elliptical, with three pairs of short horizontal branched
spines, one apical and two equatorial pairs (one dorsal and one ventral).
Basal ring roundish hexagonal, with numerous short thorns on the margin.
Jugular pores ovate, about half as broad as the ovate cardinal pores and
twice as broad as the small cervical pores.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.06.

_Habitat._--Fossil in Barbados.


4. _Semantidium signatorium_,  n. sp. (Pl. 92, fig. 7).

Sagittal ring semicircular, thorny; basal ring pentagonal, with short
spines on the margin and five stronger thorny spines on the five corners.
Jugular pores ovate, smaller than the triangular cervical pores. Cardinal
pores two to three times as large as each of the former, pentagonal.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.12.

_Habitat._--North Pacific, Station 341, depth 2300 fathoms.



Genus 410. _Clathrocircus_,[29] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Semantida# with a variable number of pores on the apical
and the basal part of the ring, symmetrically arranged, without typical
basal feet.

The genus _Clathrocircus_ comprises those Semantida in which the sagittal
ring bears not only basal pores (as in the three preceding genera) but also
apical pores (on the opposite pole of the main axis), or a variable number
of pores along the whole ring. All these pores are symmetrically arranged
in pairs. In the simplest form there are only two apical pores opposite to
four basal pores, whilst in the highest state of development the whole ring
bears two complete circles of pores. At both poles of the transverse axis
two large lateral gates remain open. If these become closed by
lattice-work, _Clathrocircus_ passes over into _Dictyospyris_.


{962}1. _Clathrocircus hexaporus_, n. sp.

Sagittal ring circular, smooth, with three pairs of pores (one apical and
two basal). The two apical pores are triangular with two lateral spines,
and correspond to the two mitral gates of the Tympanida. The four basal
pores form a hexagonal basal plate, with six lateral spines, and correspond
to the four basal pores of _Semantrum_; the two jugular are pear-shaped,
and half as broad as the two triangular cardinal pores.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.06.

_Habitat._--Cosmopolitan; Atlantic, Pacific, many Stations, surface.


2. _Clathrocircus octoporus_, n. sp.

Sagittal ring elliptical, smooth, with four pairs of pores (two apical and
two basal). The four apical pores are of nearly equal size, subcircular,
and form a regular cross around the apical pole. The four basal pores are
ovate, and form a quadrangular plate, armed with marginal thorns; the two
jugular pores are somewhat smaller than the two cardinal pores.

_Dimensions._--Height of the sagittal ring 0.11, breadth 0.08.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


3. _Clathrocircus decaporus_, n. sp.

Sagittal ring ovate, thorny, with five pairs of pores (two apical and three
basal). The four apical pores are roundish and form a cross. The six basal
pores are triangular and form a hexagonal plate with thorny margin; the two
jugular pores are somewhat larger than the two cervical, and half as broad
as the two cardinal pores.

_Dimensions._--Height of the sagittal ring 0.09, breadth 0.07.

_Habitat._--North Pacific, Station 256, depth 2950 fathoms.


4. _Clathrocircus stapedius_, n. sp. (Pl. 92, fig. 8).

Sagittal ring ovate, smooth, with six pairs of pores (two apical and four
basal). The four apical pores are of nearly equal size and form a
quadrangular mitral plate with two large lateral horns. The eight basal
pores are of very different size (the four central far larger than the two
anterior and the two posterior), and form a hexagonal basal plate, also
with two large lateral horns. The four branched lateral horns (two upper
and two lower) form together an incomplete frontal ring.

_Dimensions._--Height of the sagittal ring 0.1, breadth 0.08.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


{963}5. _Clathrocircus dictyospyris_, n. sp. (Pl. 92, fig. 9).

Sagittal ring ovate, thorny, with eight pairs of pores. The four apical and
the four basal pores are elliptical and far larger than the four dorsal and
the four ventral pores. Resembles a _Dictyospyris_ with open lateral gates.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.06.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


6. _Clathrocircus multiforis_, n. sp. (Pl. 92, fig. 10).

Sagittal ring circular, smooth, with ten to twelve pairs of roundish pores,
forming together a complete lattice-girdle with two parallel circular rows
of pores. Four larger of these are the four gates of the basal ring (two
jugular and two cardinal pores).

_Dimensions._--Diameter of the ring 0.1 to 0.15, breadth 0.03 to 0.05.

_Habitat._--Central Pacific, Stations 263 to 274, depth 2350 to 2925
fathoms.



Subfamily 2. CORTINISCIDA, Haeckel.

_Definition._--#Semantida# with large, typical, regularly disposed basal
feet (originally three cortinar feet, one odd caudal and two paired
pectoral).



Genus 411. _Cortiniscus_,[30] n. gen.

_Definition._--#Semantida# with three typical basal feet (an odd caudal
foot and two paired lateral or pectoral feet).

The genus _Cortiniscus_ is of peculiar importance, as the common ancestral
form of the _Cortiniscida_, or those Semantida in which the basal ring is
provided with typical, regularly disposed basal feet--three, four, or six.
Since these typical basal feet (or "cortinar feet") are preserved in the
greater number of all NASSELLARIA, determining their triradial structure,
they possess a great morphological value. _Cortiniscus_ exhibits the same
three primary feet as _Cortina_, from which it differs in the production of
two or more basal pores (between the odd caudal and the paired lateral
feet).


1. _Cortiniscus tripodiscus_, n. sp. (Pl. 92, fig. 11).

Sagittal ring ovate, thorny, with three prominent, distorted edges; its
dorsal rod nearly straight and vertical, with one or two pairs of short
thorns; its ventral rod strongly curved, with three or four pairs of
divergent thorns. Basal ring larger than the sagittal ring, with two
semicircular gates and obliquely ascending halves, which on the inner and
lower edge are smooth, {964}on the outer and upper thorny. Apical horn and
the three divergent feet nearly equal, straight, about as long as the
sagittal ring, with three thorny edges.

_Dimensions._--Height of the sagittal ring 0.1 to 0.12, breadth 0.07 to
0.09.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.


2. _Cortiniscus dipylaris_, n. sp. (Pl. 92, fig. 13).

Sagittal ring nearly semicircular, with prominent distorted edges and six
pairs of small roundish papillate tubercles (three pairs on the straight
dorsal, three on the curved ventral rod). Apical horn short and stout, with
a tuberculate knob. Basal ring smaller than the sagittal ring with two
elliptical gates. Three feet short and stout, irregularly branched like a
cauliflower, with numerous short papillate tubercles.

_Dimensions._--Height of the sagittal ring 0.11, breadth 0.08.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Cortiniscus tripylaris_, n. sp.

Sagittal ring elliptical, smooth. Apical horn conical, smooth. Basal ring
larger than the sagittal ring, with three elliptical gates of equal size;
two paired, posterior (jugular pores) between the basal parts of the caudal
foot and the two pectoral feet, and an odd, anterior (sternal pore) between
the basal parts of the two pectoral feet and a connecting horizontal convex
sternal bow.

_Dimensions._--Height of the sagittal ring 0.09, breadth 0.06.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


4. _Cortiniscus tetrapylaris_, n. sp.

Sagittal ring elliptical, with four pairs of short branched thorns, two
posterior on the straight dorsal, and two anterior on the curved ventral
rod. Basal ring smaller than the sagittal ring, with four triangular gates;
the two anterior (jugular pores) a little smaller than the two posterior
(cardinal pores). Apical horn and the three divergent feet shorter than the
sagittal ring, irregularly branched, with curved, often tuberculate
branches.

_Dimensions._--Height of the sagittal ring 0.08 to 0.12, breadth 0.06 to
0.1.

_Habitat._--Fossil in Barbados.


5. _Cortiniscus typicus_, n. sp. (Pl. 92, fig. 12).

Sagittal ring ovate, thorny, with three distorted edges; dorsal rod nearly
straight and vertical prolonged upwards into a stout thorny apical horn,
downwards into the caudal foot. Basal ring smaller than the sagittal ring,
with four elliptical or nearly triangular gates; the two anterior (jugular
pores) about half as large as the two posterior (cardinal pores). Three
feet of equal size, thorny, divergent, straight or slightly curved, about
as long as the diameter of the sagittal ring.

_Dimensions._--Height of the sagittal ring 0.14 to 0.18, breadth 0.1 to
0.12.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, at various depths.



{965}Genus 412. _Stephaniscus_,[31] n. gen.

_Definition._--#Semantida# with four typical basal feet (two sagittal and
two lateral or pectoral feet).

The genus _Stephaniscus_ differs from the preceding _Cortiniscus_ in the
production of a fourth (sternal) foot, and therefore exhibits the same
relation to it that _Stephanium_ among the Stephanida bears to _Cortina_.
It differs from _Stephanium_, in the production of a basal ring, with pores
or gates between the bases of the basal feet. Two of these feet are
sagittal (the posterior caudal and the anterior sternal foot), whilst the
other two are lateral or pectoral (right and left). The basal lattice-plate
exhibits either two pores ("jugular gates") or four pores (two anterior
jugular and two posterior cardinal gates).


1. _Stephaniscus tetrapodius_, n. sp.

Sagittal ring nearly circular, smooth, with a short conical apical horn.
Basal ring square, smooth, with two triangular gates. Four feet simple,
equal, conical, divergent, about as long as the diameter of the ring.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.07.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.


2. _Stephaniscus quadrifurcus_, n. sp. (Pl. 92, fig. 14).

Sagittal ring subcircular, thorny with a small thorny apical horn. Basal
ring also nearly circular, with two large semicircular gates and a few
small thorns.  All four feet curved and forked, the fork-branches again
ramified, with numerous short curved and pointed branches.  The two lateral
feet (right and left) are larger and more branched than the two sagittal
feet (sternal and caudal foot).

_Dimensions._--Height of the sagittal ring 0.12, breadth 0.1.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Stephaniscus quadrigatus_, n. sp. (Pl. 92, fig. 15).

Sagittal ring oblique, ovate, with three prominent thorny edges; its dorsal
rod nearly straight and vertical, the ventral rod strongly curved; apex
with a small curved horn. Basal ring with a few short thorns and four gates
of different size; the two anterior (jugular pores) ovate or nearly
triangular, two-thirds as broad as the two posterior subcircular or
pentagonal (cardinal pores). All {966}four feet simple, curved, with three
edges, the posterior (caudal) foot larger, the anterior (sternal) foot
smaller than the two lateral (pectoral) feet.

_Dimensions._--Height of the sagittal ring 0.09, breadth 0.07.

_Habitat._--Tropical Atlantic, Station 351, surface.


4. _Stephaniscus medusinus_, n. sp.

Sagittal ring elliptical, thorny, with a larger apical horn. Basal ring
nearly square, with short marginal thorns and four large ovate gates of
nearly equal size. All four feet of equal size divergent, curved,
irregularly branched, with short curved branches.

_Dimensions._--Height of the sagittal ring 0.13, breadth 0.09.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms. Fossil in
Barbados.



Genus 413. _Semantiscus_,[32] n. gen.

_Definition._--#Semantida# with six typical basal feet (two sagittal, two
pectoral, and two tergal feet).

The genus _Semantiscus_ may be the archetype of those NASSELLARIA which
exhibit six typical basal feet, in combination with the sagittal ring.
Three of these are the primary feet of _Cortina_ and _Cortiniscus_, the
other three are secondary productions between the former. The basal ring
may possess either two, four, or six basal pores.


1. _Semantiscus hexapodius_, n. sp. (Pl. 92, fig. 16).

Sagittal ring elliptical, with a large branched apical horn. Basal ring
small, square, with two small triangular gates (or jugular pores). From its
periphery there arise six short and stout cylindrical feet, one very large
(caudal) from the posterior corner, two tergal on each side, two opposite
(pectoral) from the lateral corners, and one odd sternal from the anterior
corner. All six spines bear a bunch of ten to twenty stout pointed conical
branches, partly simple, partly forked.

_Dimensions._--Height of the sagittal ring 0.12, breadth 0.08.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Semantiscus hexaspyris_, n. sp. (Pl. 92, fig. 18).

Sagittal ring semicircular, broad, latticed, with two pairs of irregular
dorsal and two pairs of ventral pores. The dorsal rod is straight and
vertical, prolonged upwards into a short serrate apical horn, downwards
into a straight linear caudal foot. The ventral rod is curved and prolonged
into a similar sternal foot. Basal ring hexagonal, with four ovate gates
(two smaller jugular and two larger cardinal pores); its four lateral
corners prolonged into four curved thorny lateral feet (two {967}anterior
larger pectoral, and two posterior smaller tergal feet). This species may
be regarded as a commencing _Hexaspyris_ or _Liriospyris_.

_Dimensions._--Height of the sagittal ring 0.08, breadth 0.06.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Semantiscus hexapylus_, n. sp. (Pl. 92, fig. 17).

Sagittal ring ovate, thorny, with a small apical horn. Basal ring with six
roundish or nearly triangular gates; the two jugular pores are smaller than
the two cardinal and larger than the two cervical pores. The separating
bars between these six pores are prolonged into six straight, thorny widely
divergent feet; three larger feet (the caudal and the two pectoral) with a
pair of apophyses, three smaller between them simple (the sternal and the
two tergal feet).

_Dimensions._--Height of the sagittal ring 0.13, breadth 0.09.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



Family #L. CORONIDA#, Haeckel.

  _Triostephida_, Haeckel, 1881, Prodromus, p. 445.

_Definition._--STEPHOIDEA with two crossed vertical rings, perpendicular
one to the other (the primary sagittal and the secondary frontal ring).
Usually their common base bears a horizontal basal ring, but a mitral ring
(or a horizontal ring at the apex) is never developed.

The family #Coronida# comprises those #Stephoidea# in which the primary
sagittal ring (of the Stephanida and Semantida) becomes crossed by a second
vertical ring, the lateral or frontal ring. Between these two vertical
meridian rings, perpendicular to one another, four large apertures remain
constantly open, the "lateral" gates. But besides these four constant
openings, usually (excepting only in the Zygostephanida) other gates are
developed on the common base of the two crossed rings, produced by a third,
horizontal, basal ring. These basal gates are the same which we have found
already in the Semantida.

The distinction of the Coronida from the other #Stephoidea# is always easy.
In the Stephanida and Semantida, the frontal ring, or the second meridian
ring, which we find in all Coronida, is never developed. On the other hand
these latter never exhibit the typical "mitral ring," or the second, upper,
horizontal ring, which distinguishes the Tympanida.

We distinguish here, among the Coronida, four different subfamilies, which
perhaps afterwards may be better separated as families. Of these four
groups the Zygostephanida and Acanthodesmida exhibit the nearest
relationship to the Stephanida, whilst the Eucoronida and Trissocyclida
possess a closer affinity with the Semantida.

{968}The Zygostephanida, constituting the first subfamily, exhibit four
large gates only, and differ from all other Coronida in the absence of a
basal ring and of basal gates. Therefore the skeleton is entirely composed
of two crossed vertical rings, perpendicular to one another; the first is
the primary or sagittal ring (inherited from the Stephanida), the second is
the new lateral or frontal ring. The four large lateral gates are either
quite simple (_Zygostephanus_) or partly closed by loose and irregular
lattice-work (_Zygostephanium_). The Zygostephanida may be derived directly
from the Stephanida by development of lateral branches forming a frontal
ring. They commonly possess the same characteristic spines or branches, and
the same typical difference between the straight dorsal rod and convex
ventral rod of the sagittal ring, which we found in the greater number of
Stephanida. The frontal ring is commonly elliptical or kidney-shaped, and
much larger than the ovate sagittal ring.

The Acanthodesmida, forming the second subfamily of Coronida, differ from
all other members of this family in the possession of a large simple basal
gate, surrounded by a simple horizontal basal ring. Only this ring is
complete, whilst the two crossed vertical meridian rings (the primary
sagittal and the secondary frontal ring) are incomplete, both truncated at
the base by the basal ring. Therefore there remain here between the three
rings five large gates (recognised previously by Johannes Müller in 1856 in
_Acanthodesmia_): four lateral gates (the same as in the Zygostephanida)
and one central basal gate. The latter is always quite simple and serves
for the emission of the pseudopodia, arising from the basal pole of the
central capsule. The four lateral gates are either quite simple
(_Coronidium_) or partly closed by irregular loose lattice-work
(_Acanthodesmia_). The subfamily Acanthodesmida may be derived either
directly from the Stephanida (by development of a central basal gate) or
from the Eucoronida (by loss of the basilar part of the sagittal ring).

The Eucoronida, the third subfamily, are the most important group of the
Coronida; their numerous species are much more frequent and more widely
distributed than those of the other three subfamilies. They may be derived
immediately from the Semantida by the development of a lateral or frontal
ring. This remains incomplete in the basal part, whilst the two other
rings, perpendicular to it (the vertical sagittal ring and the horizontal
basal ring), are complete. Therefore the shell constantly exhibits six
large open gates between the three rings; four lateral gates (the same as
in the Zygostephanida and Acanthodesmida) and two basal gates (inherited
from _Semantis_); the latter correspond to the "jugular pores" of the
#Spyroidea# and #Cyrtoidea#; they remain constantly simple. The four
lateral gates may also remain simple (_Eucoronis_) or they may become
partly closed by irregular loose lattice-work (_Plectocoronis_). The
remarkable genus _Podocoronis_ is distinguished by the development of
typical descending basal feet, which are regularly disposed and correspond
to the typical "cortinar feet" of the other NASSELLARIA. There may be
developed either two lateral feet (as lower {969}prolongations of the
segments of the frontal ring), or three feet (one caudal and two pectoral,
as in _Cortina_ and _Cortiniscus_), or four feet (two sagittal and two
lateral, as in _Stephanium_ and _Stephaniscus_), or six feet (two sagittal,
two pectoral, two tergal, as in _Semantiscus_), sometimes numerous feet (as
in _Petalospyris_ and _Anthocyrtis_, &c.).

The Trissocyclida represent the fourth and last subfamily of Coronida,
distinguished from all others in the possession of three complete rings,
perpendicular one to another, and of eight large gates separated by them.
Two of the three rings are vertical (the primary sagittal and the secondary
frontal ring), the third is horizontal (the basal ring). The four upper
gates correspond to the four lateral gates of the preceding three
subfamilies; the four lower gates are the same as the four basal gates of
_Semantrum_ (two primary jugular and two secondary cardinal gates);
therefore the Trissocyclida may be derived directly from these Semantida by
development of a complete frontal ring. Probably the two jugular gates were
originally smaller than the two cardinal, but usually they have become
equal. In _Tristephanium_ (the common ancestral form of the Trissocyclida)
and in the closely allied _Tricyclidium_ the four basal gates remain
smaller than the four lateral gates. But in two other genera,
_Trissocircus_ and _Trissocyclus_, the four lower or basal gates reach the
same size as the four upper or lateral gates; therefore all eight gates
become equal and the basal ring becomes equatorial. In the most regular
species of the latter genera also the three rings become perfectly equal
and cannot be any longer distinguished. Here the original bilateral (or
dipleuric) fundamental form of the shell passes over into a regular cubic
or octahedral form (with three equal, isopolar axes, perpendicular one to
another). The eight large gates of the Trissocyclida usually remain simple
(_Tristephanium_, _Trissocircus_), but sometimes they become partly closed
by loose lattice-work (_Tricyclidium_, _Trissocyclus_).

The original rings, and the secondary rods or bars, composing the loose
framework of the Coronida are either roundish (with circular or elliptical
transverse section) or three-edged (with triangular transverse section),
rarely quadrangular or provided with distorted edges. The branches or
spines arising from them, are either simple or branched, and offer a great
variety in number, form, and disposition. The most important forms are
those which develop the three typical basal feet of _Cortina_, _e.g._,
_Podocoronis cortina_ (Pl. 97, fig. 2).

The _Central Capsule_ of the Coronida is the same as in the other
#Stephoidea# (comp. p. 937), and offers all those characteristic
peculiarities of "Monopylea" which we have mentioned above in the general
description of the NASSELLARIA (p. 890). Usually it is spherical or
ellipsoidal, often violin-shaped or bilobed, with a sagittal constriction.
The porochora of its basal pole is in close contact with the base of the
sagittal ring.

{970}_Synopsis of the Genera of Coronida._

  -------------------------------------------------------------------------
  I. Subfamily Zygostephanida. Four lateral gates (no basal gate).
  -------------------------------------------------------------------------
  Two meridional rings     }Four lateral gates
   (sagittal and frontal)  } simple,                 414. _Zygostephanus_.
   complete, perpendicular }
   to one                  }Four lateral gates
   another (no basal       } partly latticed,        415. _Zygostephanium_.
   ring).
  -------------------------------------------------------------------------
  II. Subfamily Acanthodesmida.
      Five large gates (four lateral and one simple basal).
  -------------------------------------------------------------------------
  Two meridional rings     }Four lateral gates
   (sagittal and frontal)  } simple,                 416. _Coronidium_.
   incomplete, both        }
   truncated by the        }Four lateral gates
   complete horizontal     } partly latticed,        417. _Acanthodesmia_.
   basal ring.
  -------------------------------------------------------------------------
  III. Subfamily Eucoronida. Six large gates (four lateral and two basal).
  -------------------------------------------------------------------------
  Two rings (the      {Basal ring     {Gates simple, 418. _Eucoronis_.
   sagittal meridional{ without larger{
   ring and the       { descending    {Gates partly
   horizontal basal   { feet.         { latticed,    419. _Plectocoronis_.
   ring) complete, the{
   frontal meridian   {Basal ring with large,
   ring incomplete.   { regularly disposed,
                      { descending feet. Gates
                      { simple,                      420. _Podocoronis_.
  -------------------------------------------------------------------------
  IV. Subfamily Trissocyclida.
      Eight large gates (four upper lateral and four lower basal).
  -------------------------------------------------------------------------
  Two meridional      {Four upper     {Gates simple, 421. _Tristephanium_.
   rings (sagittal and{ gates larger  {
   frontal) and the   { than the      {Gates partly
   horizontal basal   { four lower.   { latticed,    422. _Tricyclidium_.
   ring complete. All {
   three complete     {All eight gates{Gates simple, 423. _Trissocircus_.
   rings perpendicular{ of equal size.{
   to one another.    {               {Gates partly
                                      {latticed,     424. _Trissocyclus_.



Subfamily 1. ZYGOSTEPHANIDA, Haeckel, 1881, Prodromus, p. 446.

_Definition._--#Coronida# with four large lateral gates, without basal
gate. Skeleton composed of two complete vertical rings, perpendicular one
to another--the primary sagittal and the secondary frontal ring.



Genus 414. _Zygostephanus_,[33] Haeckel, 1862, Monogr. d. Radiol., p. 268.

_Definition._--#Coronida# with four large, simple, lateral gates, without
basal gate and lattice-work. Skeleton composed of two simple meridional
rings, perpendicular to one another.

The genus _Zygostephanus_, founded by me in 1862 for the Mediterranean
_Zygostephanus mülleri_, is the simplest and most primitive of all the
Coronida, and may {971}therefore be regarded as the common ancestral form
of this family. The simple skeleton is composed of two meridional rings
only, perpendicular one to another--a sagittal and a frontal ring.



Subgenus 1. _Zygostephus_, Haeckel, 1881, Prodromus, p. 446.

_Definition._--The two vertical rings of nearly equal height, therefore
without sagittal constriction.


1. _Zygostephanus dissocircus_, n. sp. (Pl. 93, fig. 1).

Both rings elliptical, of nearly equal height, smooth, without spines.
Frontal ring somewhat longer than the sagittal. No sagittal constriction.

_Dimensions._--Height of the rings 0.07, breadth 0.1.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.


2. _Zygostephanus serratus_, n. sp.

Both rings elliptical, of nearly equal height, with a serrate prominent
edge on the outer convexity (in the transverse section three-edged). No
sagittal constriction.

_Dimensions._--Height of the rings 0.08, breadth 0.12.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Zygostephanus mülleri_, Haeckel.

  _Zygostephanus mülleri_, Haeckel, 1862, Monogr. d. Radiol., p. 268, Taf.
  xii. fig. 2.

Both rings elliptical, of nearly equal height, armed with numerous (about
fifty) slender curved spines, as long as the radius of the rings; commonly
each ring with twelve pairs of divergent spines. No sagittal constriction.

_Dimensions._--Height of the rings 0.06, breadth 0.1.

_Habitat._--Mediterranean (Messina), surface.


4. _Zygostephanus ramosus_, n. sp.

Both rings elliptical, of nearly equal height, armed with numerous branched
spines, which are arranged on each ring in two divergent rows; the branches
of the spines are curved and partly protect the open gates. No sagittal
constriction.

_Dimensions._--Height of the rings 0.07, breadth 0.09.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.



{972}Subgenus 2. _Zygostephaniscus_, Haeckel, 1881, Prodromus, p. 446.

_Definition._--The two vertical rings of different heights; the frontal
ring higher than the sagittal ring, therefore with a sagittal constriction
in the median plane.


5. _Zygostephanus reniformis_, n. sp.

Frontal ring kidney-shaped, in the upper half convex, in the lower concave,
in the latter with a deep sagittal constriction, armed with numerous
irregular short spines. Sagittal ring thicker and lower, only two-thirds as
high, with four pairs of short divergent spines (two ventral and two dorsal
pairs).

_Dimensions._--Height of the frontal ring 0.13, breadth 0.2.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


6. _Zygostephanus violina_, n. sp.

Frontal ring violin-shaped, on the upper and the lower margin concave, with
a deep sagittal constriction, armed with numerous irregular spines, which
are partly simple, partly branched. Sagittal ring thicker and lower, only
half as high, with a few short conical spines at the apical and basal
poles.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.18.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


7. _Zygostephanus bicornis_, n. sp. (Pl. 93, fig. 2).

Frontal ring violin-shaped, on the upper and the lower margin concave, with
a deep sagittal constriction; its two halves pentagonal. Between numerous
smaller spines there arise from the frontal ring six groups of larger
branched spines, two odd in the corners of the highest points (curved like
two horns), two branched pairs on the prominent lateral corners (at right
and left), and two pairs in the corners of the lowest points (like four
branched basal feet). Sagittal ring only two-thirds as high, with four
pairs of irregular spines.

_Dimensions._--Height of the frontal ring 0.11, breadth 0.16.

_Habitat._--South Pacific Station 300, depth 1375 fathoms.



Genus 415. _Zygostephanium_,[34] Haeckel, 1881, Prodromus, p. 446.

_Definition._--#Coronida# with four large, partly latticed, lateral gates,
without basal gate. Skeleton composed of two meridional rings perpendicular
to each other.

The genus _Zygostephanium_ differs from the preceding ancestral genus
_Zygostephanus_ in the development of lattice-work along the two crossed
rings, produced by their anastomosing branches. Therefore the four large
lateral gates between them, which are quite simple, in the preceding genus
here become more or less fenestrated.


{973}1. _Zygostephanium dizonium_, n. sp. (Pl. 93, fig. 3).

  _Tympaniscus dizonius_, Haeckel, 1882, Manuscript.

Both rings elliptical, of nearly equal height, smooth, without spines.
Sagittal ring with four pairs of small pores (two apical pairs and two
basal pairs). Frontal ring with three pairs of small pores (one pair
lateral, one pair above and one pair below).

_Dimensions._--Height of the frontal ring 0.08, breadth 0.12.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


2. _Zygostephanium paradictyum_, n. sp. (Pl. 93, fig. 4).

Frontal ring kidney-shaped, in the upper half convex, in the lower concave,
in the latter with a deep sagittal constriction. Sagittal ring ovate, about
two-thirds as high as the frontal ring. Both rings three-edged, armed with
numerous short and branched bristle-shaped spines, which anastomose along
their three edges and produce two series of irregular polygonal pores.

_Dimensions._--Height of the frontal ring 0.08, breadth 0.13.

_Habitat._--North Pacific, Station 236, surface.


3. _Zygostephanium constrictum_, n. sp.

Frontal ring violin-shaped, concave on the upper and lower margins, with a
deep sagittal constriction. Sagittal ring ovate, about two-thirds as high
as the frontal ring. Both rings covered with numerous branched irregular
spines, which partly anastomose along the edges of the rings, and produce
small irregular polygonal pores.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.18.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Subfamily 2. ACANTHODESMIDA, Haeckel, 1881, Prodromus, p. 445.

_Definition._--#Coronida# with five large gates (four lateral and one
basal). Skeleton composed of three rings, perpendicular one to another, two
of which are vertical and incomplete (the primary or lateral, and the
secondary or frontal), the third is horizontal and complete (the tertiary
or basal ring).



Genus 416. _Coronidium_,[35] Haeckel, 1881, Prodromus, p. 445.

_Definition._--#Coronida# with five large simple gates (four lateral and
one basal). Skeleton composed of two incomplete meridional rings and one
complete basal ring, without lattice-work.

{974}The genus _Coronidium_ and the following, nearly allied
_Acanthodesmia_, form together the peculiar subfamily of
Acanthodesmida--not in the wider sense in which I first founded this group
(1862, Monogr. d. Radiol., p. 265), but in the restricted sense, which is
exactly defined in my Prodromus (1881, p. 445). According to this
definition, the shell is composed of three different rings, perpendicular
to one another; only one of these is complete, the simple horizontal basal
ring; the two others are incomplete and vertical (the primary or sagittal
and the secondary or frontal ring). Therefore there remain constantly
between the three rings five characteristic large openings or gates; four
of these are lateral (between the halves of the two meridional rings), the
fifth is basal, enclosed by the horizontal basal ring. The longest known
type of this subfamily is _Acanthodesmia vinculata_, the five
characteristic gates of which are clearly distinguished by its discoverer,
Johannes Müller ("Das Gehäuse besteht nur aus den Leisten zwischen fünf
grossen Lücken"). The Acanthodesmida may be derived from the Eucoronida by
reduction of the basilar rod of the sagittal ring. If in _Eucoronis_ this
basal rod be lost, _Coronidium_ arises.


1. _Coronidium dyostephanus_, n. sp. (Pl. 82, fig. 7).

Frontal ring elliptical, with few scattered thorns, twice as broad as high,
and three times as broad as the smooth rhombic basal ring. Sagittal ring
semicircular, very stout, twice as thick as the two other rings, with short
lateral thorns (in the figure seen from the apical pole, which exhibits a
four-lobed dimple). Basal gate rhombic.

_Dimensions._--Height of the frontal ring 0.08, breadth 0.16.

_Habitat._--Central Pacific, Station 263, depth 2650 fathoms.


2. _Coronidium diadema_, n. sp. (Pl. 82, fig. 8).

Frontal ring kidney-shaped, one and a half times as broad as high, with a
slight sagittal constriction. Sagittal ring ovate, smaller, about of the
same size as the elliptical basal ring. Rods of all three rings
cylindrical, bearing numerous short and stout curved spines, partly simple,
partly branched. Four bunches of larger spines on the four corners of the
basal ring, and one very large bunch on the apical pole. Basal gate
elliptical, one and a half times as broad as long.

_Dimensions._--Height of the frontal ring 0.13, breadth 0.18.

_Habitat._--Indian Ocean (Madagascar), Rabbe, surface.


3. _Coronidium cervicorne_, n. sp. (Pl. 82, fig. 1).

Frontal ring kidney-shaped, twice as broad as high, one and a half times as
broad as the elliptical basal ring, both with a slight sagittal
constriction. Sagittal ring ovate. All three rings {975}(in the figure seen
from the apical pole) with cylindrical rods, armed with numerous stout
spines, branched like a deer's antler. Basal gate rather oblong, twice as
broad as long.

_Dimensions._--Height of the frontal ring 0.08, breadth 0.16.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


4. _Coronidium acacia_, n. sp. (Pl. 82, fig. 2).

Frontal ring and sagittal ring nearly circular, of equal size, truncated at
the base. Basal ring circular, somewhat smaller. All three rings with
prominent edges, bearing bunches of short and straight pointed spines, like
those of an Acacia. Basal gate circular.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.14.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.



Genus 417. _Acanthodesmia_,[36] J. Müller, 1856, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 485.

_Definition._--#Coronida# with five large, partly latticed gates (four
lateral and one basal). Skeleton composed of two incomplete, partly
fenestrated meridional rings, and one complete basal ring.

The genus _Acanthodesmia_, the oldest known form of all Coronida, differs
from the preceding _Coronidium_, its ancestral form, in the development of
irregular loose lattice-work along the rings, and therefore bears to it the
same relation that _Zygostephanium_ does to _Zygostephanus_. The first
species described by Johannes Müller, _Acanthodesmia vinculata_ ("with five
large gates between the bars of the shell") remains the true type of this
genus; the second species described by him (_Acanthodesmia dumetum_)
belongs to the Plectanida (_Polyplecta_).


1. _Acanthodesmia vinculata_, J. Müller.

  _Acanthodesmia vinculata_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 30, Taf. i. figs. 4-6 (_non_ 7).

  _Lithocircus vinculatus_, J. Müller, 1856, Monatsber. d. k. preuss. Akad.
  d. Wiss. Berlin, p. 484.

Frontal ring violin-shaped, one and a half times as broad as high, with a
sagittal constriction. Sagittal ring ovate, smaller. The four gates between
the two rings are partly fenestrated by a few thin threads, irregularly
branched and connecting the two rings. A few short thorns are scattered
here and there. Basal gate elliptical.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.18.

_Habitat._--Mediterranean (Nice), Atlantic (Canary Islands), surface.


{976}2. _Acanthodesmia ceratospyris_, n. sp.

Frontal ring violin-shaped, one and a half times as broad as high, with a
deep sagittal constriction. Sagittal ring semicircular, half as high as the
frontal ring. The four gates between the two rings are partly fenestrated
by anastomosing branches of the numerous, irregularly branched spines,
which cover all three rings. Basal gate nearly circular, smaller than the
sagittal ring.

_Dimensions._--Height of the frontal ring 0.08, breadth 0.12.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


3. _Acanthodesmia corona_, n. sp. (Pl. 93, fig. 5).

Frontal ring kidney-shaped, nearly twice as broad as high, with a flat
sagittal constriction. Sagittal ring semicircular. The four gates between
the two rings are partly fenestrated by an arachnoidal network, composed of
thin, irregularly branched threads, arising from the rings. The edges of
all three rings are armed with irregular thorns. Basal gate circular,
larger than the sagittal ring.

_Dimensions._--Height of the frontal ring 0.08, breadth 0.14.

_Habitat._--Indian Ocean (Madagascar), Rabbe, surface.


4. _Acanthodesmia mülleri_, n. sp.

Frontal ring kidney-shaped with a deep sagittal constriction. Sagittal ring
ovate. The four gates between the two rings irregularly fenestrated, with a
few large polygonal meshes. Edges of the rings with a few scattered thorns.
Basal gate violin-shaped.

_Dimensions._--Height of the frontal ring 0.1, breadth 0.16.

_Habitat._--Tropical Atlantic, Station 347, surface.



Subfamily 3. EUCORONIDA, Haeckel, 1881, Prodromus, p. 445.

_Definition._--#Coronida# with six large gates (four lateral and two basal
gates). Skeleton composed of three rings perpendicular to one another, two
of which are complete (the vertical sagittal, and the horizontal basal
ring); the third is incomplete (the vertical frontal ring).



Genus 418. _Eucoronis_,[37] Haeckel, 1881, Prodromus, p. 445.

_Definition._--#Coronida# with six large simple gates (four lateral and two
basal). Skeleton composed of two complete rings (the sagittal and basal)
and one incomplete (frontal) ring. Basal ring without typical feet.

{977}The genus _Eucoronis_ and the following two nearly allied genera
(_Plectocoronis_ and _Podocoronis_) compose together the important
subfamily Eucoronida. In this typical main group of Coronida the shell is
constantly composed of three rings and six gates. The vertical sagittal
ring and the horizontal basal ring are complete (as in the Semantida); the
vertical frontal ring is incomplete. Between these three rings remain six
large open gates, the four upper (or lateral) are always much larger than
the four lower (or basal gates). _Eucoronis_ may be derived from _Semantis_
by development of the frontal ring.



Subgenus 1. _Acrocoronis_, Haeckel, 1881, Prodromus, p. 445.

_Definition._--Rings smooth or rough, armed with numerous short spines or
thorns.


1. _Eucoronis perspicillum_, n. sp. (Pl. 82, fig. 6).

Frontal ring elliptical, twice as broad as high, with a slight constriction
at the apical pole, armed with three pairs of short conical spines, one
apical pair (near the constriction) and two lateral pairs (one upper and
one lower pair). Sagittal ring of the same height, half the breadth and
double the thickness, also armed with three pairs of spines (one basal, one
dorsal, and one ventral pair).

_Dimensions._--Height of the frontal ring 0.11, breadth 0.22.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


2. _Eucoronis lævigata_, n. sp.

Frontal ring elliptical, smooth, one and a half times as broad as high,
without sagittal constriction, with horizontal basal gates. Sagittal ring
of the same height and thickness, also elliptical and smooth. No spines on
either of the smooth rings.

_Dimensions._--Height of the frontal ring 0.1, breadth 0.15.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


3. _Eucoronis nephrospyris_, n. sp. (Pl. 82, fig. 5).

Frontal ring kidney-shaped, in the upper half convex, in the lower concave,
with a sagittal constriction (often much deeper than in the specimen
figured). Sagittal ring ovate, about two-thirds as high as the frontal
ring. Rods of both rings without edges, cylindrical, armed with numerous
short conical thorns.

_Dimensions._--Height of the frontal ring 0.1 to 0.12, breadth 0.15 to
0.18.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, many
Stations, surface and at various depths.


{978}4. _Eucoronis angulata_, n. sp. (Pl. 82, fig. 3).

Frontal ring violin-shaped, twice as broad as high, on the upper and the
lower margin concave, with a deep sagittal constriction. Sagittal ring
pentagonal, with straight horizontal basal rod, two-thirds as high as the
frontal ring. Rods of both rings with sharp prominent edges, bearing
numerous short pyramidal spines.

_Dimensions._--Height of the frontal ring 0.09, breadth 0.17.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Subgenus 2. _Lithocoronis_, Haeckel, 1881, Prodromus, p. 445.

_Definition._--Rings armed with numerous large, branched or arborescent
spines.


5. _Eucoronis cervicornis_, n. sp.

Frontal ring kidney-shaped, in the upper half convex, in the lower concave,
with sagittal constriction. Sagittal ring ovate, two-thirds as high as the
frontal ring. Both rings armed with numerous stout spines, irregularly
branched like a deer's antler. (Very similar to _Coronidium cervicorne_,
Pl. 82, fig. 1, which I formerly confounded with it, but differing in the
complete sagittal ring, which in the latter form is incomplete and has lost
its basal part.)

_Dimensions._--Height of the frontal ring 0.12, breadth 0.2.

_Habitat._--Central Pacific, Station 264, surface.


6. _Eucoronis arborescens_, n. sp.

Frontal ring kidney-shaped, with a deep sagittal constriction in the
concave basal part. Sagittal ring ovate, half as high as the frontal ring.
Both rings armed with numerous thin, richly branched and arborescent spines
(branches much thinner and more numerous than in the preceding and
following species).

_Dimensions._--Height of the frontal ring 0.15, breadth 0.25.

_Habitat._--Equatorial Atlantic, Station 247, surface.


7. _Eucoronis challengeri_, n. sp. (Pl. 82, fig. 4).

  _Lithocoronis challengeri_, Haeckel, 1881, Prodromus, p. 445.

Frontal ring violin-shaped, one and a half times as broad as high, with a
strong sagittal constriction. Sagittal ring nearly circular, two-thirds as
high as the frontal ring. Both rings armed with numerous irregularly
branched spines. (The specimen figured, with red central capsule and
numerous xanthellæ, was observed living by me at the Canary Islands.)

_Dimensions._--Height of the frontal ring 0.1 to 0.12, breadth 0.14 to
0.17.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface and at various
depths.



{979}Genus 419. _Plectocoronis_,[38] Haeckel, 1881, Prodromus, p. 445.

_Definition._--#Coronida# with six large, partly latticed gates (four
lateral and two basal). Skeleton composed of two complete rings (the
sagittal and basal) and one incomplete (frontal) ring. Basal ring without
developed typical feet.

The genus _Plectocoronis_ differs from the preceding _Eucoronis_, its
ancestral form, in the development of loose irregular lattice-work along
the two meridional rings, and therefore bears to it the same relation that
_Acanthodesmia_ does to _Coronidium_. If the lattice-work become more
complete and close the gates, these Coronida pass over directly into
#Spyroidea# (Zygospyrida).


1. _Plectocoronis anacantha_, n. sp.

Basal ring and frontal ring elliptical, without sagittal constriction.
Sagittal ring ovate. The frontal and sagittal rings are bordered on both
edges with an incomplete series of small irregular pores. All three rings
smooth, without spines.

_Dimensions._--Height of the frontal ring 0.1, breadth 0.16.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


2. _Plectocoronis triacantha_, n. sp.

Basal ring and frontal ring nearly circular, without sagittal constriction.
Sagittal ring elliptical, prolonged at the apex into an apical horn from
which two branched lateral bows descend and unite with the uppermost parts
of the frontal ring. Four other small bows descend from the lowermost parts
of the latter and unite with the basal ring. From the lateral corners of
the basal ring descend two short vertical feet. (May be regarded as derived
from _Podocoronis toxarium_, Pl. 83, Fig. 7, by development of the bows
connecting the rings.)

_Dimensions._--Height of the frontal ring 0.11, breadth 0.13.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


3. _Plectocoronis pentacantha_, n. sp. (Pl. 93, fig. 6).

Basal ring and frontal ring kidney-shaped, with deep sagittal constriction.
Sagittal ring ovate, prolonged at the apex into an oblique horn. From the
edges of the angular rings delicate threads arise, which anastomose and
form irregular arachnoidal meshes, partly closing the four open lateral
gates. Two basal gates simple. From the four nodal points of the basal ring
there arise four, short diverging feet, comparable to rudimentary cortinar
feet (two lateral from the frontal ring and two sagittal from the primary
ring, as basal prolongations).

_Dimensions._--Height of the frontal ring 0.12, breadth 0.18.

_Habitat._--Central Pacific, Station 271, surface.



{980}Genus 420. _Podocoronis_,[39] Haeckel, 1881, Prodromus, p. 445.

_Definition._--#Coronida# with six large gates (four lateral and two
basal). Skeleton composed of two complete rings (the sagittal and basal)
and one incomplete (frontal) ring. Basal ring provided with typical,
regularly disposed, descending feet (cortinar feet).

The genus _Podocoronis_ differs from the two preceding nearly allied genera
in the development of typical radial feet on the basal ring, which by their
regular disposition and their general appearance among the #Spyroidea# and
#Cyrtoidea# obtain great morphological importance. According to the
different number and disposition of these basal feet (or "cortinar feet"),
the following subgenera may be distinguished (regarded in my Prodromus,
1881, p. 445, as separate genera):--_Dipocoronis_ with two lateral feet,
_Tripocoronis_ with three cortinar feet (most important!), _Tetracoronis_
with four crossed feet, _Hexacoronis_ with six radial feet, _Stylocoronis_
with numerous (8 or more feet). These subgenera have important relations to
the corresponding genera of Zygospyrida.



Subgenus 1. _Dipocoronis_, Haeckel, 1881, Prodromus, p. 445.

_Definition._--Basal ring with two descending lateral feet (right and left)
as prolongations of the frontal ring.


1. _Podocoronis dipodiscus_, n. sp.

Basal ring nearly circular, with two conical, straight, parallel descending
feet, which are direct lateral prolongations of the subcircular frontal
ring, and half as long as it. The ovate sagittal ring bears at the apex a
short conical vertical horn. All rings nearly smooth.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.14.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Podocoronis toxarium_, n. sp. (Pl. 83, fig. 7).

Basal ring elliptical, with two descending, slightly curved conical feet,
lateral prolongations of the subcircular frontal ring. The ovate sagittal
ring bears at the apex a cylindrical vertical horn, which is connected by
two descending lateral arches (or galear arches) with the uppermost part of
the frontal ring.

_Dimensions._--Height of the frontal ring 0.1, breadth 0.13.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2900 fathoms.



{981}Subgenus 2. _Tripocoronis_, Haeckel, 1881, Prodromus, p. 445.

_Definition._--Basal ring with three descending feet (one caudal and two
pectoral).


3. _Podocoronis cortiniscus_, n. sp. (Pl. 97, fig. 2).

Basal ring violin-shaped, with three straight divergent thorny feet, about
as long as the ovate sagittal ring. The dorsal part of the latter is
straight, vertical, and prolonged downwards into the caudal foot, upwards
into a stout, thorny, vertical apical horn. The ventral part is
semicircular and gives off the lateral branches, forming the kidney-shaped
sagittal ring. All the rings and their apophyses are armed with stout
thorns. This and the following tripodal species may be directly derived
from _Cortina_.

_Dimensions._--Height of the frontal ring 0.1, breadth 0.15.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


4. _Podocoronis tripodiscus_, n. sp.

Basal ring kidney-shaped, with three large divergent curved feet, nearly
twice as long as the semicircular sagittal ring. The straight dorsal part
of the latter is prolonged downwards into the caudal foot, upwards into a
large branched apical horn, curved backwards. Differs from the preceding
species mainly in the longer curved apophyses and in the larger
violin-shaped frontal ring.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.2.

_Habitat._--North Pacific, Station 238, surface. Fossil in Barbados.



Subgenus 3. _Tetracoronis_, Haeckel, 1881, Prodromus, p. 445.

_Definition._--Basal ring with four descending feet (two sagittal and two
lateral).


5. _Podocoronis tetrapodiscus_, n. sp.

Basal ring kidney-shaped, with four stout and straight divergent feet,
about as long as the sagittal ring; two of them are lateral and arise from
the basal corners of the violin-shaped frontal ring (at its junction with
the basal ring); two are sagittal, and arise from the basal corners of the
semicircular sagittal ring (one posterior caudal and one anterior sternal).
The straight dorsal part of the sagittal ring is prolonged upwards into an
apical horn. All the rings are thorny.

_Dimensions._--Height of the frontal ring 0.15, breadth 0.25.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



Subgenus 4. _Hexacoronis_, Haeckel

_Definition._--Basal ring with six radial descending feet (two sagittal,
two pectoral, and two tergal feet).


{982}6. _Podocoronis hexapodiscus_, n. sp.

Basal ring violin-shaped, with six conical, vertically descending feet,
half as long as the sagittal ring; two of them are sagittal (arising from
the two basal corners of the sagittal ring, caudal and sternal feet); the
other four are lateral, and prolongations of the forked basal parts of the
frontal ring, which is inserted on the basal ring with two forked branches;
the anterior correspond to the pectoral, the posterior to the tergal feet
of _Hexaspyris_. All the rings are thorny.

_Dimensions._--Height of the frontal ring 0.11, breadth 0.17.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.



Subgenus 5. _Stylocoronis_, Haeckel.

_Definition._--Basal ring with numerous (eight to twelve or more)
descending feet.


7. _Podocoronis petalospyris_, n. sp.

Basal ring violin-shaped, with ten to twelve flat lamellar, vertically
descending feet, about as long as the ovate sagittal ring. Frontal ring
twice as broad as long, elliptical. All rings nearly smooth. Similar to a
_Petalospyris_ without lattice-work.

_Dimensions._--Height of the frontal ring 0.1, breadth 0.2.

_Habitat._--Fossil in Barbados.


8. _Podocoronis polypodiscus_, n. sp.

Basal ring elliptical, with fifteen to eighteen conical, curved, descending
feet, half as long as the ovate sagittal ring. Frontal ring kidney-shaped,
one and a half times as broad as long. All the rings armed with short
conical spines.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.18.

_Habitat._--Central Pacific, Station 273, depth 2350 fathoms.



Subfamily 4. TRISSOCYCLIDA, Haeckel, 1881, Prodromus, p. 446.

_Definition._--#Coronida# with eight large gates (four superior lateral and
four inferior basal). Skeleton composed of three complete rings,
perpendicular to one another; two of which are vertical (the primary or
sagittal and the secondary or frontal ring), the third is horizontal (the
tertiary or basal ring).



Genus 421. _Tristephanium_,[40] Haeckel, 1881, Prodromus, p. 445.

_Definition._--#Coronida# with eight large, simple gates of different
sizes; the four upper or lateral gates larger than the four lower or basal
gates. Skeleton composed of three simple complete rings, perpendicular to
one another.

{983}The genus _Tristephanium_, and the three following genera derived from
it, represent together the interesting subfamily of Trissocyclida
(Prodromus, 1881, p. 446). These differ from all other Coronida in the
possession of three complete rings, perpendicular to one another. The first
of these is the vertical sagittal ring, the second the vertical frontal
ring, and the third the horizontal basal ring. Since these three rings lie
in the three dimensive planes, they are perpendicular to one another; and
between them remain eight large open gates. Originally the four upper or
lateral gates (corresponding to those of _Zygostephanus_) are much larger,
the four lower or basal gates (corresponding to those of _Semantrum_) much
smaller; but afterwards the latter may reach the size of the former, so
that the basal ring becomes equatorial (in _Trissocircus_ and
_Trissocyclus_). The common ancestral form of the Trissocyclida
(_Tristephanium_) may be derived directly either from _Semantrum_ (by
complete development of the frontal ring) or from _Eucoronis_ (by complete
development of four basal gates).



Subgenus 1. _Triostephus_, Haeckel, 1881, Prodromus, p. 445.

_Definition._--Sagittal and frontal ring of different size and form.


1. _Tristephanium dimensivum,_ n. sp. (Pl. 93, fig. 9).

Sagittal ring ovate, with a large thorny apical horn, smaller than the two
other rings. Frontal ring violin-shaped, with a deep sagittal constriction.
Basal ring also violin-shaped, in the sagittal axis constricted. Its four
gates (two jugular and two cardinal) of nearly equal size. All three rings
angular, armed with scattered, stout, thorny spines, which are larger in
the basal half.

_Dimensions._--Height of the frontal ring 0.08, breadth 0.12.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


2. _Tristephanium octopyle,_ n. sp. (Pl. 93, fig. 8).

Sagittal ring ovate, nearly smooth, smaller than the two other rings.
Frontal ring kidney-shaped, with a deep basal constriction. Basal ring
violin-shaped. The jugular gates about half as large as the cardinal gates.
Rods of the rings cylindrical, with few scattered thorns.

_Dimensions._--Height of the frontal ring 0.09, breadth 0.14.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Tristephanium hertwigii,_ Haeckel.

  _Acanthodesmia hertwigii_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. pp. 499, 539, Taf. xxxii. figs. 9_a_-9_c_.

Sagittal ring ovate or nearly semicircular; its dorsal rod straight, smooth
(fig. 9_c_, _a_), its ventral rod (_b_) curved, thorny. Frontal ring much
larger, thorny, violin-shaped, with a slight sagittal {984}constriction.
Basal ring smaller than the sagittal ring, thorny, kidney-shaped, with four
different gates; the two cardinal pores much larger than the two jugular
pores. (The four basal pores are often much larger than in the specimen
figured by Bütschli. Also the number, form, and size of the spines is very
variable.)

_Dimensions._--Height of the frontal ring 0.07 to 0.09, breadth 0.17 to
0.2.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Tristephaniscus_, Haeckel, 1881, Prodromus, p. 445.

_Definition._--Sagittal and frontal ring of equal size and form.


4. _Tristephanium quadricorne_, n. sp. (Pl. 93, fig. 7).

Sagittal and frontal ring of equal size and form, larger than the circular
basal ring. From the four corners, in which the latter crosses the two
former, arise four strong, divergent spines, branched like a deer's antler.
Some smaller spines are scattered on the rings, and a bunch of four spines
arises on the apical pole. The four upper gates are triangular, the four
lower nearly semicircular, the latter of equal size, half as large as the
former.

_Dimensions._--Height of the frontal ring 0.13, breadth 0.14.

_Habitat._--South Atlantic, Station 342, depth 1445 fathoms.



Genus 422. _Tricyclidium_,[41] Haeckel, 1881, Prodromus, p. 446.

_Definition._--#Coronida# with eight large, partly fenestrated gates; the
four upper or lateral gates larger than the four lower or basal gates.
Skeleton composed of three latticed complete rings, perpendicular to one
another.

The genus _Tricyclidium_ differs from the preceding _Tristephanium_, its
ancestral form, in the development of loose rudimentary lattice-work along
the rings, and therefore bears to it the same relation that _Plectocoronis_
does to _Eucoronis_. It may pass directly over into _Dictyospyris_.


1. _Tricyclidium dictyospyris_, n. sp. (Pl. 93, fig. 13).

Sagittal ring ovate, twice as thick as the two other larger rings, which
become very thin, thread-like at the lateral junction, and are both
slightly violin-shaped, in the middle sagittal plane constricted; the
frontal ring larger than the basal. All three rings bear small scattered
spines, which are irregularly branched, and by anastomoses of the
thread-like branches form small irregular meshes along the rings. The four
basal gates are of equal size.

_Dimensions._--Height of the frontal ring 0.11, breadth 0.15.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.


{985}2. _Tricyclidium semantrum_, n. sp.

Sagittal ring ovate, smaller than the violin-shaped frontal ring and larger
than the elliptical basal ring. All three rings of nearly equal thickness,
armed with short irregular branches, which are partly connected, and
forming small irregular meshes along the rings. The four basal gates are of
different sizes; the two anterior (jugular) gates only half as large as the
two posterior (cardinal) gates.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.18.

_Habitat._--South Atlantic, Station 348, depth 2450 fathoms.



Genus 423. _Trissocircus_,[42] Haeckel, 1881, Prodromus, p. 446.

_Definition._--#Coronida# with eight large simple gates of equal size.
Skeleton composed of three simple complete rings, perpendicular to one
another.

The genus _Trissocircus_, and the following nearly allied _Trissocyclus_,
differ from the two preceding ancestral genera in the remarkable growth of
the four basal gates, which reach the size of the lateral gates. Therefore
both hemispheres of the shell (the upper or apical and the lower or basal)
here become equal and the basal ring becomes equatorial. Sometimes even all
three rings attain the same size, so that it is difficult or impossible to
distinguish them. In this curious case the Coronida exhibit a striking
resemblance to some #Sphæroidea#.



Subgenus 1. _Tricircarium_, Haeckel.

_Definition._--Sagittal ring smaller than the two other rings, which are
both elliptical.


1. _Trissocircus lentellipsis_, n. sp. (Pl. 93, fig. 10).

All three rings elliptical, of different sizes, smooth, without spines. The
sagittal ring is the smallest, but two to three times as thick as the other
two rings, which have the larger (transverse) axis common. The smaller
(sagittal) axis of the sagittal ring is also the smaller axis of the
equatorial ring, whilst the larger (principal) axis of the former is the
smaller axis of the frontal ring.

_Dimensions._--Height of the frontal ring 0.07, breadth 0.1.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.


2. _Trissocircus binellipsis_, n. sp. (Pl. 83, fig. 6).

Sagittal ring circular, smaller than the other two rings, which are both
equal, elliptical, slightly constricted on the poles of the principal and
transverse axes. The axis of the circular sagittal {986}ring is the shorter
axis of the frontal and equatorial ring, and about half as long as their
longer axis. All three rings smooth, without spines.

_Dimensions._--Height of the frontal ring 0.08, breadth 0.12.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Trissocircus octostoma_ (Pl. 93, fig. 11).

Sagittal ring circular, smaller than the other two rings, which are both
equal, elliptical, distinctly constricted at the poles of the principal and
transverse axes. The axis of the circular sagittal ring is the shorter axis
of the frontal and equatorial ring, about one-third shorter than their
longer axis. All three rings armed with short, irregularly branched spines.

_Dimensions._--Height of the frontal ring 0.1, breadth 0.12.

_Habitat._--Indian Ocean, Ceylon (Belligemma), Haeckel, surface.



Subgenus 2. _Tricirconium_, Haeckel.

_Definition._--All three rings equal, circular.


4. _Trissocircus octahedrus_, n. sp.

All three rings equal, circular, smooth, their rods cylindrical (in the
transverse section circular). From each pole of the three equal axes arises
a short conical spine; these six spines correspond to the six corners of a
regular octahedron.

_Dimensions._--Diameter of all three rings 0.08, thickness 0.006.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


5. _Trissocircus globus_, n. sp. (Pl. 82, fig. 13).

All three rings equal, circular, thorny; their rods prismatic (in the
transverse section triangular), with three sharp dentated edges and
scattered branched thorns. From each pole of the three equal axes (which
correspond to the three axes of a regular octahedron) arises a bunch of
larger spines.

_Dimensions._--Diameter of all three rings 0.12, thickness 0.01.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Genus 424. _Trissocyclus_,[43] Haeckel, 1881, Prodromus, p. 446.

_Definition._--#Coronida# with eight large, partly fenestrated gates of
equal size. Skeleton composed of three complete latticed rings,
perpendicular to one another.

The genus _Trissocyclus_ differs from its nearly allied ancestral form
_Trissocircus_ only in the development of small anastomosing branches along
the edges of the rings. The incomplete lattice-work, produced by these
anastomoses, partly protects the eight large gates. The three rings are
either of equal or of different sizes.



{987}Subgenus 1. _Tricyclarium_, Haeckel.

_Definition._--Sagittal ring circular, smaller than the other two rings,
which are both elliptical.


1. _Trissocyclus stauroporus_, n. sp. (Pl. 83, fig. 5).

Sagittal ring circular, smaller than the other two equal elliptical rings.
On each of the six corners (or crossing points of every two rings) are
developed four small pores, forming a cross around the poles of the three
axes. All three rings smooth, without spines.

_Dimensions._--Height of the frontal ring 0.09, breadth 0.13.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


2. _Trissocyclus triaxonius_, n. sp.

Sagittal ring circular, smaller than the two other equal elliptical rings.
From the edges of all three rings are developed small branches, which by
irregular ramification and anastomoses form small irregular meshes along
the rings. Similar to _Trissocircus octostoma_, but with thicker rings; it
may be developed from the latter species by connection of the branches
which border the rings.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.15.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.



Subgenus 2. _Tricyclonium_, Haeckel.

_Definition._--All three rings equal, circular.


3. _Trissocyclus sphæridium_, n. sp. (Pl. 93, fig. 12).

All three rings equal, circular, thorny; their rods prismatic, three-sided,
with three denticulate edges; the teeth of the lateral edges become
branched, and form by anastomoses of the branches small irregular meshes,
which partly protect the eight large open gates.

_Dimensions._--Diameter of the three rings 0.16, thickness 0.012.

_Habitat._--Indian Ocean, Belligemma, Ceylon (Haeckel), surface



Family LI. #TYMPANIDA#, Haeckel.

  _Parastephida_, Haeckel, 1881, Prodromus, p. 446.

_Definition._--#Stephoidea# with two parallel horizontal rings, an upper
mitral and a lower basal ring; both connected by complete or incomplete
vertical rings, or by parallel vertical columellæ.

{988}The family #Tympanida# (or Parastephida) differs from the other
#Stephoidea# in the development of two horizontal rings, which lie in
horizontal planes and arise from the upper and the lower poles of the
primary sagittal ring. Therefore the same formation, which we found in the
Semantida on the basal pole only of the main axis, here takes place also on
its apical pole. On both poles arise at each side from the sagittal ring
two corresponding pairs of curved branches: the lateral ends of the
opposite branches (dorsal and ventral branch) become united in the frontal
plane and so form two complete horizontal rings. The upper ring, composed
of the superior or mitral branches, may be called the mitral ring, the
lower ring, formed by the inferior or basal branches, the basal ring. Both
rings are commonly of nearly equal size, more rarely of different sizes.
Their connection is effected either by the primary (sagittal) ring only, or
also by secondary vertical rings, a frontal ring in the lateral plane, or
some diagonal meridian rings between the latter and the former. These
vertical rings, which connect both horizontal rings in the form of
"columellæ," may be either complete or incomplete; in the latter case their
apical and basal parts are lost, the dorsal and ventral parts only being
preserved.

The Tympanida develop a great variety of different forms, greater than in
the three other families of #Stephoidea#, so that we may distinguish here
not less than sixteen genera and seventy-two species. Hitherto only three
species were known: _Prismatium tripleurum_, figured in 1862 in my
Monograph, _Tympanidium barbadense_, figured by Bury in the "fossil
Polycystins of Barbados," and _Tympaniscus fibula_, described in 1875 by
Ehrenberg as a _Ceratospyris fibula_. The number of species in this large
and richly developed group will be considerably augmented by further
researches. A great many of them exhibit remarkable relations to different
NASSELLARIA. For better survey of the whole family we distinguish here four
subfamilies, the first of which (Protympanida) is probably the common
ancestral group of the other three. They may have been derived originally
either from the Semantida or directly from the Stephanida.

The first subfamily, Protympanida, exhibits a complete primary or vertical
sagittal ring, bearing on the upper part a horizontal mitral ring, on the
lower part a horizontal basal ring. Therefore the gates of these two
parallel rings become bisected by the sagittal ring, each divided into a
right and a left half. The sagittal ring itself becomes divided by the two
horizontal rings into four parts or rods; two opposite of these are more or
less vertical; the dorsal (posterior) and the ventral (anterior) rod; the
two other rods are more or less horizontal; the mitral (upper) and the
basal (lower) rod.

In _Protympanium_ (Pl. 93, fig. 14), the simplest and most primitive form
of Tympanida, the connection of the two horizontal rings is effected only
by the dorsal and ventral rods of the sagittal ring forming two parallel
more or less vertical "columellæ." In all other Protympanida accessory
columellæ are developed between the latter. In the greater number we find
two secondary columellæ in the lateral plane, being the lateral
{989}segments of an incomplete frontal ring (_Acrocubus_, Pl. 93, figs.
15-17). Between the latter and the former there are sometimes developed
four tertiary columellæ, as segments of two crossed incomplete diagonal
rings (_Tympanidium_, Pl. 94, figs. 1, 18). At other times we find six
columellæ; here probably the frontal ring is cleft into halves on each side
(_Tympaniscus_, Pl. 94, figs. 4-7). Some genera are distinguished by the
development of an equatorial ring, or a third horizontal ring (between the
upper mitral and the lower basal ring); this equatorial ring is either
complete (_Microcubus_ Pl. 94, figs. 8-10) or incomplete, developed only
laterally (_Octotympanum_, Pl. 94, figs. 2, 3). The genus _Toxarium_ (Pl.
93, figs. 18-20) is distinguished by the development of accessory pairs of
bows in the frontal plane, upper or galear bows and lower or thoracal bows,
remarkable as beginnings of the accessory joints, which we distinguish in
many #Spyroidea# and #Cyrtoidea# as "galea and thorax."

The second subfamily of Tympanida are the Paratympanida, in which the two
horizontal rings become closed by lattice-work. The numerous columellæ
connecting the two rings are here either divergent (_Paratympanum_, with
two unequal rings, Pl. 94, fig. 14) or parallel and vertical
(_Lithotympanum_, with two equal rings, Pl. 83, fig. 1). The shell of the
latter assumes the form of a drum.

A third small subfamily, Dystympanida, is represented by a single genus
only, _Dystympanium_ (Pl. 94, figs. 15, 16). Here only the upper or mitral
ring is closed by lattice-work, whilst the lower or basal ring exhibits
quite a simple opening, a large "basal gate" which has probably arisen by
loss of the basilar rod of the sagittal ring. These curious forms exhibit a
remarkable resemblance to some Monocyrtida, and also to the _Dictyocha_
(PHÆODARIA).

The fourth subfamily, the Eutympanida, are distinguished by the simple wide
aperture of the two horizontal rings; the upper enclosing a simple "mitral
gate," the lower a simple "basal gate." Here probably the two horizontal
parts of the sagittal ring (the upper mitral rod and the lower basilar rod)
are lost by reduction; its two vertical parts (the dorsal and ventral rods)
only remaining and forming the two parallel columellæ, which connect the
two horizontal rings (_Parastephanus_, Pl. 93, fig. 21). In this group also
secondary columellæ are commonly developed between the two rings,
alternating with the two primary columellæ. _Pseudocubus_ (Pl. 94, figs.
11, 12), resembling an obelisk, exhibits four divergent columellæ; the two
sagittal of these are probably the vertical parts of the primary ring,
whilst the two lateral are the halves of an incomplete frontal ring. In
_Lithocubus_ (Pl. 82, fig. 12) the four columellæ are parallel and
vertical, the two rings being equal; the shell here assumes the form of a
geometrical cube. _Prismatium_ is distinguished by three parallel
columellæ; two of these are probably parts of a frontal ring, whilst the
third is the remains of a reduced sagittal ring. In _Circotympanum_ (Pl.
94, fig. 17) and in _Lithotympanum_ (Pl. 82, fig. 11) the number of the
columellæ is augmented, there being six to eight or more; in the former
they are divergent {990}(the two rings being of different sizes), in the
latter parallel (the two rings being equal); the fundamental form of the
former is a truncated pyramid, of the latter a prism.

Comparing these differences between the four subfamilies of Tympanida, we
may suppose that the common ancestral group are the Protympanida, derived
from the Semantida by the formation of a mitral ring. If the two horizontal
rings become closed by lattice-work, the Paratympanida arise. When the
mitral ring only becomes latticed, the basal ring being simple, the
Dystympanida originate. Finally, the fourth subfamily, the Eutympanida, may
be derived from the Protympanida by the loss of the two horizontal parts of
the sagittal ring.

The two horizontal rings (upper mitral and lower basal) and the two
vertical rings (primary sagittal and secondary frontal), which thus compose
the loose framework of the Tympanida, are rarely smooth, commonly armed
with spines or branches, similar to those of the Coronida. The rods or bars
are either roundish (with circular transverse section) or angular (commonly
with triangular transverse section). The paired branches of the two
vertical rings often preserve the characteristic arrangement inherited from
the Semantida and Stephanida. The two horizontal rings sometimes exhibit
typical apophyses, which recur in the #Spyroidea# and #Cyrtoidea#. The
mitral ring may possess one odd apical horn and two paired frontal horns
(Pl. 93, figs. 16, 17, 19, 23). The basal ring sometimes bears the three
typical feet of _Cortina_ (Pl. 93, figs. 16, 22), one odd caudal foot and
two paired pectoral feet. Sometimes a fourth (sternal) foot is developed
(Pl. 94, fig. 4), at other times only two lateral feet (Pl. 94, figs. 5,
6).

_Synopsis of the Genera of Tympanida._

  -------------------------------------------------------------------------
  I. Subfamily Protympanida.
     Two horizontal rings (upper mitral ring and lower basal ring)
        bisected by the complete sagittal ring.
  -------------------------------------------------------------------------
  Two horizontal rings          {One complete sagittal
   connected by two             { ring (no frontal
   columellæ.                   { ring),              425. _Protympanium_.

                }               {No galear and
  Two horizontal}               { thoracal bows,      426. _Acrocubus_.
  rings         }No equatorial  {
  connected     } ring.         {Galear and
  by four       }               { thoracal bows,      427. _Toxarium_.
  columellæ     }
  (the halves of}               {Equatorial ring
  the sagittal  }An equatorial  { complete,           428. _Microcubus_.
  and the       } ring.         {
  frontal ring).}               {Equatorial ring
                }               { incomplete,         429. _Octotympanum_.

                                {Six columellæ
  Two horizontal rings          { (three meridional
   connected by six or eight    {  rings),            430. _Tympaniscus_.
   columellæ (three or four     {
   vertical rings).             {Eight columellæ
                                { (four meridional
                                { rings),             431. _Tympanidium_.
  -------------------------------------------------------------------------
  II. Subfamily Paratympanida. Two horizontal rings fenestrated.
  -------------------------------------------------------------------------
                                {Two rings unequal
  Two horizontal rings closed   { (columellæ
   by a lattice-plate,          { divergent),         432. _Paratympanum_.
   connected by numerous        {
   columellæ.                   {Two rings equal
                                { (columellæ
                                { parallel),          433. _Lithotympanum_.



  III. Subfamily Dystympanida. Mitral ring fenestrated, basal ring simple.
  ------------------------------------------------------------------------
  Two horizontal rings    } Mitral ring closed by a
   connected by numerous  } lattice-plate, basal
   (six  to eight or more } ring simple,              434. _Dystympanium_.
   columellæ).            }

  IV. Subfamily Eutympanida. Two horizontal rings (upper mitral ring and
  lower basal ring) simple. Apical and basal parts of the sagittal ring
  lost.
  -----
                          {Two columellæ (parts of
  Two horizontal rings    { the sagittal ring),       435. _Parastephanus_.
   connected by two or    {
   three columellæ (four  {Three columellæ (parts of
   or five open gates).   { the half sagittal and
                          { the frontal ring),        436. _Prismatium_.

                          {              {Two rings
                          {              { unequal,   437. _Pseudocubus_.
                          {Four          {
  Two horizontal rings    { columellæ    {Two rings
   connected by four or   {              { equal,     438. _Lithocubus_.
   more columellæ (six or {
   eight or more open     {              {Two rings
   gates).                {Six to eight  { unequal,   439. _Circotympanum_.
                          { or more      {
                          { columellæ.   {Two rings
                          {              { equal,     440. _Eutympanium_.



Subfamily 1. PROTYMPANIDA, Haeckel.

_Definition._--#Tympanida# with two bisected horizontal rings, connected by
the complete vertical sagittal ring. (The upper mitral ring and the lower
basal ring become divided by the complete primary or sagittal ring into two
horizontal symmetrical gates, two mitral gates on the apical and two basal
gates on the basal pole.)



Genus 425. _Protympanium_,[44] Haeckel, 1881, Prodromus, p. 447 (_sensu
emend._).

_Definition._--#Tympanida# with two bisected horizontal rings, connected by
two vertical columellæ.

The genus _Protympanium_, is the most simple form of all Tympanida, and
probably the common ancestral form of this family. It arises from
_Lithocircus_ by the development of two horizontal rings, perpendicular to
the primary sagittal ring. The upper or mitral ring arises by lateral union
of two pairs of superior branches, the lower or basal ring by union of two
pairs of basal branches of the primary vertical ring.


1. _Protympanium primordiale_, n. sp.

Mitral and apical ring of equal size, elliptical, smooth, somewhat smaller
than the connecting thorny sagittal ring.

_Dimensions._--Diameter of the two horizontal rings 0.12, of the sagittal
ring 0.15.

_Habitat._--Central Pacific, Stations 263 to 274, at various depths.


{992}2. _Protympanium amphipodium_, n. sp. (Pl. 93, fig. 14).

Mitral and apical rings of equal size, thin, elliptical, smooth, larger
than the broad connecting sagittal ring. The latter bears on the apical and
on the basal pole two divergent straight spines (lying in the frontal
plane), the two apical (or horns) somewhat smaller and not so spiny as the
two basal spines (or feet). In the frontal plane there arise from the two
horizontal rings on each side two small opposite spines (remnants or
beginnings of the lateral frontal ring?).

_Dimensions._--Diameter of the two horizontal rings 0.11, of the sagittal
ring 0.07.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Protympanium trissocircus_, n. sp.

Mitral ring smaller than the basal ring; both rings circular, rough.
Sagittal ring in size between the two former. All three rings covered with
very small thorns.

_Dimensions._--Diameter of the mitral ring 0.08, of the sagittal ring 0.1,
of the basal ring 0.12.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Genus 426. _Acrocubus_,[45] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Tympanida# with two bisected horizontal rings, connected by
four vertical columellæ. No equatorial ring.

The genus _Acrocubus_ is the most primitive of those remarkable Tympanida,
the skeleton of which represents more or less exactly the form of a
geometrical cube. A simple complete sagittal ring bears on the superior and
on the inferior part two opposite pairs of lateral branches; by union of
the convergent branches of each side there arise two horizontal parallel
quadrangular rings, which are bisected by the sagittal ring. Therefore the
superior ring encloses two triangular mitral gates, the inferior two
triangular basal gates. The lateral corners of the two gates of each side
are connected by a vertical rod or columella. These two parallel columellæ
are the remaining middle parts of the secondary or frontal ring, which is
incomplete on the superior and on the inferior face of the body. If the
sagittal ring also become incomplete, by the loss of the superior and
inferior part (the anterior and posterior only remaining), then _Acrocubus_
is transformed into _Lithocubus_.



Subgenus 1. _Apocubus_, Haeckel.

_Definition._--Basal ring without descending feet.


{993}1. _Acrocubus octopylus_, n. sp. (Pl. 82, fig. 9).

Mitral ring somewhat smaller than the basal ring; both rings rhombic, with
curved outlines. Sagittal ring elliptical, with six pairs of nodulate
protuberances. Four columellæ curved. Nodal points without radial spines.

_Dimensions._--Height of the frontal ring 0.12, breadth 0.18.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Acrocubus tesseralis_, n. sp.

Mitral ring of the same size as the basal ring; both rings square, smooth,
with straight outlines. Sagittal ring also square, smooth. Four columellæ
straight. Nodal points without radial spines. The shell has the form of a
regular geometrical cube, the edges of which are represented by the rings.

_Dimensions._--Height of the frontal ring 0.1, breadth 0.11.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.



Subgenus 2. _Dipocubus_, Haeckel.

_Definition._--Basal ring with two descending feet.


3. _Acrocubus brachiatus_, n. sp.

Mitral ring smaller than the basal, both rings square, with thick straight
rods. Sagittal ring tuberculate, square, equatorial part thinner. Four
columellæ curved, the two lateral ones prolonged downwards into two
vertical parallel straight feet of half their length.

_Dimensions._--Diameter of the cube 0.12; length of the feet 0.06.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


4. _Acrocubus amphistylus_, n. sp.

Mitral and basal rings of nearly equal size, square, with thick curved
rods. Sagittal ring elliptical, in the equatorial part thinner. Frontal
ring tuberculate. Four columellæ curved, the two lateral ones prolonged
downwards into two vertical, tuberculate feet of half their length.

_Dimensions._--Diameter of the cube 0.13; length of the feet 0.07.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


5. _Acrocubus arcuatus_, n. sp. (Pl. 93, fig. 15).

Mitral and basal rings, as well as the sagittal ring, of the same form as
in the preceding nearly allied species. The two lateral columellæ are
prolonged not only downwards into two short {994}vertical feet, but also
upwards into two curved bows, which are united in a vertical ascending
horn, arising from the apical pole of the sagittal ring.

_Dimensions._--Diameter of the cube 0.14; total height 0.21.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.



Subgenus 3. _Tripocubus_, Haeckel.

_Definition._--Basal ring with three descending feet (one odd caudal and
two paired lateral).


6. _Acrocubus lasanum_, n. sp.

Mitral ring smaller than the basal, both rings square, with curved rods.
Sagittal ring ovate, prolonged upwards into an occipital simple horn,
downwards into a caudal foot. Two lateral columellæ prolonged downwards
into two pectoral feet. All three feet conical, about as long as the height
of the cube.

_Dimensions._--Diameter of the cube 0.08; length of the feet 0.07.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


7. _Acrocubus cortina_, n. sp. (Pl. 93, fig. 16).

Mitral ring smaller than the basal, both rings elliptical, with curved
rods. Sagittal ring ovate, prolonged upwards into an occipital horn,
downwards into a caudal foot, as in the preceding species. As in the
latter, also, the two lateral columellæ are prolonged downwards into two
pectoral feet, but also upwards into two convergent horns, which are united
with the occipital horn (commencing the formation of a galea). Rings and
feet somewhat thorny.

_Dimensions._--Diameter of the cube 0.16; total height 0.2.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



Subgenus 4. _Tetracubus_, Haeckel.

_Definition._--Basal ring with four descending feet (two sagittal and two
lateral).


8. _Acrocubus tetrapodius_, n. sp.

Mitral and basal rings of the same size, square, with straight rods,
sagittal ring also square. The four vertical columellæ are nearly parallel
and straight, prolonged upwards into four short conical horns, downwards
into four longer conical feet. (The shell has nearly the form of a
geometrical cube, the eight corners of which are prolonged into eight
vertical conical spines, four smaller ascending and four larger
descending.)

_Dimensions._--Diameter of the cube 0.09; length of the feet 0.06.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


{995}9. _Acrocubus amphithectus_, n. sp. (Pl. 93, fig. 17).

Mitral ring smaller than the basal, both rings elliptical, with curved
rods. Four columellæ thorny, also curved, divergent downwards, prolonged
upwards into four thorny convergent horns, downwards into four larger
branched divergent feet. The two sagittal horns and feet (anterior and
posterior) are smaller than the two lateral (right and left); therefore the
fundamental form of this species is distinctly amphithect (as in the
_Ctenophora_).

_Dimensions._--Breadth of the cube 0.12; total height 0.2.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.



Genus 427. _Toxarium_,[46] n. gen.

_Definition._--#Tympanida# with two bisected horizontal rings, connected by
four vertical columellæ. In the frontal plane two galear bows project
upwards, and two thoracal bows downwards.

The genus _Toxarium_ differs from its ancestral form _Acrocubus_ in the
development of two pairs of peculiar bows, placed in the lateral or frontal
plane; the upper pair projects above the mitral gates, and may be called
the "galear bows," the lower pair projects below the basal gates of the
cubical shell, and may be called the "thoracal bows." Both pairs are
produced originally by the development of two forked vertical spines,
arising in the frontal plane on both poles of the principal axis from the
sagittal ring (compare _Protympanium amphipodium_, Pl. 93, fig. 14). The
apical fork-branches become connected with the lateral corners of the
mitral gates, the basal branches with those of the basal gates. By
development of lattice-work between the bows and the rings some #Spyroidea#
(_Amphispyris_, &c.) may have arisen. The important genus _Toxarium_ may be
divided into three subgenera. In _Toxellium_ all the bows are simple, in
_Toxonium_, all are forked; in _Toxidium_, the galear bows are simple, the
thoracal bows forked.



Subgenus 1. _Toxellium_, Haeckel.

_Definition._--Galear and thoracal bows simple.


1. _Toxarium circospyris_, n. sp. (Pl. 88, fig. 1).

Galear and thoracal bows simple, of about the same size as the frontal bows
between them; all bows armed with scattered simple conical spines. Sagittal
constriction deep, half as long as the whole shell. Lateral outlines of the
shell nearly parallel.

_Dimensions._--Length of the shell 0.16, breadth 0.13.

_Habitat._--Central Pacific, Stations 265 to 274, depth 2350 to 2925
fathoms.


{996}2. _Toxarium subcirculare_, n. sp.

Galear and thoracal bows simple, armed with scattered simple spines of
about equal size, smaller than the smooth frontal bows between them.
Sagittal constriction very flat. Therefore the frontal perimeter of the
shell is nearly circular.

_Dimensions._--Length of the shell 0.15, breadth 0.14.

_Habitat._--North Atlantic (Antilles), Weber, surface.


3. _Toxarium thorax_, n. sp. (Pl. 93, fig. 18).

Galear bows simple, smaller than the frontal bows, and these again smaller
than the simple thoracal bows; therefore the shell increases in breadth
towards the base, and resembles the skeleton of the thorax of one of the
higher vertebrates (the bow-pairs corresponding to rib-pairs, the ventral
part of the sagittal ring to the sternum, the dorsal part to the vertebral
column). Sagittal constriction very deep. All bows are armed with
scattered, irregularly branched spines.

_Dimensions._--Length of the shell 0.17, breadth 0.2.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


4. _Toxarium constrictum_, n. sp.

Galear and thoracal bows simple, of nearly equal size, larger than the
frontal bows between them. Therefore the shell is constricted in the
equatorial plane. Sagittal constriction also deep. All bows armed with
scattered, irregularly branched spines.

_Dimensions._--Length of the shell 0.14, breadth 0.12.

_Habitat._--North Pacific, Station 236, surface.



Subgenus 2. _Toxidium_, Haeckel.

_Definition._--Galear bows simple, thoracal bows forked.


5. _Toxarium cordatum_, n. sp. (Pl. 93, fig. 19).

Galear bows simple, thoracal bows forked, both somewhat smaller than
frontal bows; all bows armed with scattered simple conical spines, mostly
developed at the thoracal bows. Both galear bows are united in a central
vertical columella, which arises from the apex of the sagittal ring, and is
prolonged into an apical horn. Therefore the sagittal constriction exists
only in the basal half of the inversely cordate shell.

_Dimensions._--Length of the shell 0.18, breadth 0.16.

_Habitat._--South Atlantic, Station 348, depth 2450 fathoms.


{997}6. _Toxarium furcatum_, n. sp.

Galear bows simple, thoracal bows forked, both somewhat broader than the
frontal bows. Shell therefore slightly constricted in the equatorial plane.
Sagittal constriction rather deep, equal in the apical and basal parts. All
bows armed with scattered spines, which are partly simple, partly forked.

_Dimensions._--Length of the shell 0.14, breadth 0.16.

_Habitat._--Central Pacific, Station 270, depth 2925 fathoms.


7. _Toxarium pedatum_, n. sp.

Galear bows simple, smaller than the frontal bows, which are again smaller
than the thoracal bows. Therefore the breadth of the shell increases
towards the base. Sagittal constriction flat in the apical part, deep in
the basal part. All bows armed with small irregularly scattered spines; at
the base six larger divergent feet (two lateral, two anterior, and two
posterior).

_Dimensions._--Length of the shell 0.17, breadth 0.15.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.



Subgenus 3. _Toxonium_, Haeckel.

_Definition._--Galear and thoracal bows forked.


8. _Toxarium costatum_, n. sp.

Galear and thoracal bows forked, smaller than the frontal bows, all bows
thorny, without larger spines. Sagittal constriction on both poles deep.
Lateral outlines of the shell nearly parallel.

_Dimensions._--Length of the shell 0.15, breadth 0.12.

_Habitat._--Indian Ocean, Socotra (Haeckel), surface.


9. _Toxarium bifurcum_, n. sp. (Pl. 93, fig. 20).

Galear and thoracal bows forked, the former smaller than the frontal bows,
the latter larger. Sagittal constriction rather flat on the apical pole,
which bears a vertical forked horn, very deep on the basal pole of the
primary ring. All bows armed with numerous spines, which are partly simple,
partly forked, and mainly developed at the basal part of the thoracal bows.

_Dimensions._--Length of the shell 0.2, breadth 0.2.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 428. _Microcubus_,[47] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Tympanida# with two bisected horizontal rings, connected by
four vertical columellæ, which are bisected again by an equatorial ring.

{998}The genus _Microcubus_ is derived from its ancestral form _Acrocubus_
by development of a third horizontal ring, which lies in the equatorial
plane, parallel to the upper mitral and the lower basal ring. Whilst these
latter are both bisected by the complete vertical sagittal ring, the
equatorial ring is complete, and connected at the poles of the sagittal
axis with the principal ring, and at the poles of the transverse axis with
the frontal ring. Therefore the shell exhibits not eight large gates as in
_Acrocubus_, but twelve, viz., four horizontal gates (two superior mitral
and two inferior basal), four upper vertical gates (between the mitral and
the equatorial ring), and four lower vertical gates (between the basal and
the equatorial ring).


1. _Microcubus dodecastoma_, n. sp. (Pl. 94, fig. 9).

All twelve gates simple, irregularly ovate or pentagonal. Frontal ring on
the sides concave, constricted by the equatorial ring. All rings curved,
armed with short irregular thorns. No larger basal spines.

_Dimensions._--Length of the shell 0.13, breadth 0.15.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750
fathoms.


2. _Microcubus pentacircus_, n. sp.

All twelve gates simple. Frontal ring on the sides convex, not constricted
by the equatorial ring. All rings tuberculate, with irregular roundish
knots. No larger basal spines. Similar to the preceding species; but the
five rings are much thicker and tuberculate (not thorny); the twelve gates
are therefore relatively smaller.

_Dimensions._--Length of the shell 0.1, breadth 0.12.

_Habitat._--Fossil in Barbados.


3. _Microcubus zonarius_, n. sp. (Pl. 94, fig. 8).

All twelve gates simple, ovate. Frontal ring on the sides convex, not
constricted by the equatorial ring, nearly twice as broad as long. All
rings thorny, very thin, except only the broad angular sagittal ring. No
larger basal spines.

_Dimensions._--Length of the shell 0.08, breadth 0.15.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


4. _Microcubus quadrupes_, n. sp.

All twelve gates simple, square. Frontal ring square, not constricted by
the equatorial ring. All rings smooth, quadrangular. Basal ring with four
short vertical conical feet, two of which (right and left) are inferior
prolongations of the frontal ring, and arise from the lateral corners of
the {999}basal gates; two others are prolongations of the sagittal ring
(sternal and caudal), and arise from the medial corners of the basal gates.
(The shell is like a small cube with four feet.)

_Dimensions._--Length of the shell 0.13, breadth 0.11.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.


5. _Microcubus cornutus_, n. sp.

Eight gates (two mitral, two basal, and four superior) simple; four
inferior gates fenestrated by arachnoidal irregular threads. Frontal ring
square, constricted on the sides by the equatorial ring. Basal ring with
four short conical vertical feet, as in the preceding species. Sagittal
ring with a vertical horn on the apex. All rings with small scattered
thorns.

_Dimensions._--Length of the shell 0.11, breadth 0.13.

_Habitat._--North Pacific, Station 235, surface.


6. _Microcubus amphispyris_, n. sp. (Pl. 94, fig. 10).

Four gates (two mitral and two basal) simple; eight lateral gates (four
superior and four inferior) fenestrated by arachnoidal irregular threads.
Frontal ring convex, not constricted by the equatorial ring. Basal ring
with six short conical divergent feet (two sagittal and four lateral).
Sagittal ring with an apical horn. (Resembles some #Spyroidea#.)

_Dimensions._--Length of the shell 0.08, breadth 0.12.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 429. _Octotympanum_,[48] n. gen.

_Definition._--#Tympanida# with two bisected horizontal rings converging
laterally and connected in the lateral poles of the equatorial plane. Eight
large gates.

The genus _Octotympanum_ differs from all other Tympanida in the peculiar
connection of the two horizontal rings, which here reach the maximum of
their growth, converge towards the equator, and come into direct contact on
the poles of the equatorial transverse axis. Therefore the shell appears to
be composed of three complete vertical meridian rings, the middle of which
(the sagittal ring) is free and simple; the two other (subfrontal) rings
are grown together at the lateral poles of the equatorial plane; commonly
at these poles there arises (on the right and left) a strong lateral spine,
and the base of this (or the crossing point of the two touching horizontal
rings) corresponds to the remnants of the shortened frontal ring. The
crown-shaped shell exhibits therefore eight large gates; two superior
(mitral) and two inferior basal gates, two larger anterior (facial) and two
larger posterior (occipital) gates. Seen from the lateral poles {1000}only
two of the former are visible, and represent the figure of a vertical 8;
seen from the sagittal poles, only two of the latter are visible, in the
form of a larger horizontal 8. _Octotympanum_ may be derived from
_Acrocubus_ by reduction of the lateral frontal ring to a knot (or
cross-point), and by maximal extension of the two parallel horizontal
rings, which become curved downwards laterally and touch at the lateral
poles.


1. _Octotympanum octospinum_, n. sp.

Mitral gates smaller than the basal gates; upper halves of the two lateral
meridional rings smaller than the lower halves. Rings with few scattered
thorns; four larger simple spines, nearly horizontal in the equatorial
plane; two on the poles of the sagittal axis, two on the poles of the
lateral axis. Four other large spines, nearly vertical at the four
lowermost basal points of the subfrontal rings.

_Dimensions._--Length of the shell 0.09, breadth 0.12.

_Habitat._--Central Pacific, Station 273, depth 2350 fathoms.


2. _Octotympanum octonarium_, n. sp. (Pl. 94, fig. 3).

Mitral gates of the same size as the basal gates; upper and lower halves of
the meridional rings of equal size. Rings armed with numerous stout,
thorny, simple and forked spines; four very large branched spines in the
equatorial plane, nearly horizontal, two on the poles of the sagittal, two
on the poles of the transverse axis, the latter curved downwards.

_Dimensions._--Length of the shell 0.1, breadth 0.2.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Octotympanum arborescens_, n. sp.

Mitral gates smaller than the basal gates, the lower halves of the lateral
rings being broader than the upper halves. Rings very spiny, armed with
numerous branched spines; ten very large arborescent spines on the lateral
rings; two on the poles of the transverse axis, eight on the prominent
corners of the diagonal axes (four upper and four lower); sagittal ring
thorny.

_Dimensions._--Length of the shell 0.8, breadth 0.16.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


4. _Octotympanum cervicorne_, n. sp. (Pl. 94, fig. 2).

Mitral and basal gates of equal size, the lower and upper halves of the two
crossed lateral rings being nearly equal. Rings armed with numerous
branched spines; two very large spines, similar to the antlers of a deer,
on the poles of the lateral axis; their branches about half as large as the
whole shell. Sagittal ring nearly smooth, with few small thorns on the
poles of the main axis.

_Dimensions._--Length of the shell 0.16, breadth 0.2.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



{1001}Genus 430. _Tympaniscus_,[49] n. gen.

_Definition._--#Tympanida# with two bisected horizontal rings, which are
connected by three vertical meridional rings (or six columellæ).

The genus _Tympaniscus_ and the following _Tympanidium_ differ from all
preceding Tympanida in the multiplication of the vertical columellæ, which
connect the two horizontal bisected rings. _Tympaniscus_ exhibits six
columellæ, which may be regarded as halves of three meridional rings. Only
one, however, of these is complete (the sagittal ring, which bisects the
mitral and the basal ring); the two other meridional rings (placed in
diagonal planes) may be regarded as produced by lateral bifurcation of an
incomplete frontal ring; this appears to be already foreshadowed in the
preceding _Octotympanum_.


1. _Tympaniscus corona_, n. sp.

Basal ring larger than the mitral ring, with numerous irregular short
spines but without descending feet. Six columellæ strongly curved, in the
lower half thicker and thorny; the four lateral much thinner than the two
sagittal. Apex of the jointed sagittal ring with a conical horn.

_Dimensions._--Length of the shell 0.08, breadth 0.11.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Tympaniscus bipes_, n. sp.

Basal ring of about the same size as the mitral ring, with two lateral
descending feet, which are parallel and vertical, simple, without spur,
half as long as the sagittal ring. The latter is ovate, twice as long and
broad as the two circular frontal rings.

_Dimensions._--Breadth of the shell 0.14, length 0.09.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


3. _Tympaniscus dipodiscus_, n. sp. (Pl. 94, figs. 5, 6).

Basal ring smaller than the mitral ring, with two lateral descending feet,
which are nearly parallel and vertical, obtuse, about as long as the
sagittal ring, and which bear on the outside a horizontal spur. Sagittal
ring hexagonal, very stout, with a caudal appendix at the base, and with a
small sagittal arch, bearing a stout spinulate double knob at the apex. The
two subfrontal rings depressed, twice as broad as high, on the outside
thorny, connected at each side in the lower half by a double transverse
arch.

_Dimensions._--Breadth of the shell 0.18, length 0.08 (with spines 0.18).

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


{1002}4. _Tympaniscus tripodiscus_, n. sp. (Pl. 94, fig. 7).

Basal ring of about the same size as the mitral ring, with three large and
stout divergent feet (two lateral and one caudal). Sagittal ring stout,
broader than the two spiny subsagittal rings; the upper part of the latter
bears two ascending arches, which are united with the large apical horn
arising from the apex of the sagittal ring. Six columellæ nearly vertical,
slightly curved on the outside; their lateral edges armed with numerous
simple or forked spines.

_Dimensions._--Breadth of the shell 0.1, total length 0.12.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


5. _Tympaniscus quadrupes_, n. sp. (Pl. 94, fig. 4).

Basal ring larger than the mitral ring, with four short vertical
three-sided pyramidal feet of equal size (two lateral and two sagittal);
the feet are three-sided pyramidal, with finely denticulate median edges,
and bear at the base a horizontal thorny spur. Sagittal ring at the apex
with a very large cross-shaped horn, bearing two horizontal thorny lateral
branches; the horn is supported by an anterior and a posterior arch. Six
columellæ strongly curved and dentate.

_Dimensions._--Breadth of the shell 0.15, length 0.12.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.


6. _Tympaniscus fibula_, Haeckel.

  _Ceratospyris fibula_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 3.

Basal ring of about the same size as the mitral ring, with six large
conical descending feet; these are prolongations of the six columellæ,
nearly of the same length, slightly divergent, and bear at the base a
strong horizontal spur. The six columellæ are strongly curved, spiny, and
bear above small arches, which are united with the apical horn of the
sagittal ring.

_Dimensions._--Breadth of the shell 0.09, height 0.05; total height 0.09.

_Habitat._--Fossil in Barbados.


7. _Tympaniscus dodecaster_, n. sp.

Basal ring of the same size as the mitral ring, with six very large and six
alternating smaller, slightly divergent, curved feet, about as long an the
shell; the larger are the basal prolongations of the six curved, thorny
columellæ. Mitral ring spiny, not overgrown with arches, as in the similar
preceding species.

_Dimensions._--Length of the shell 0.08, breadth 0.12.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



{1003}Genus 431. _Tympanidium_,[50] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Tympanida# with two bisected horizontal rings, which are
connected by four vertical meridional rings (or eight columellæ).

The genus _Tympanidium_ differs from all other Protympanida in the
development of four vertical rings, placed in four different meridional
planes. Only one of these is complete, the primary sagittal ring; the three
others are incomplete, inserted on the two horizontal rings, which are
formed by the paired mitral and basal branches of the sagittal ring; one of
these three lies in the frontal plane, the two others in diagonal
meridional planes (between the frontal and sagittal). The shell therefore
exhibits twelve large gates, four of which are horizontal (the two superior
mitral and the two inferior basal gates); the eight others are vertical,
separated by the eight columellæ, or the halves of the four meridional
rings. In the subgenus _Tympanomma_ the number of gates amounts to sixteen,
the four lateral gates being bisected by an incomplete equatorial ring. The
genus _Tympanidium_ may be derived from _Acrocubus_ by development of the
two diagonal rings (between the frontal and sagittal).



Subgenus 1. _Tympanura_, Haeckel.

_Definition._--Shell with twelve gates; the four lateral gates simple.


1. _Tympanidium foliosum_, n. sp. (Pl. 94, fig. 1).

Shell with twelve gates; the four lateral gates simple. Basal gates of the
shell larger than the mitral gates. Sagittal ring ovate, much smaller than
the three other meridional rings, which are armed with numerous large
elegant spines, bearing a lanceolate leaf on a thin pedicle. The sagittal
ring bears a bunch of similar spines only at the apex, and on both poles of
the sagittal axis (in the equator) a single forked spine, with two thorny
branches.

_Dimensions._--Length of the shell 0.09 (with spines 0.25), breadth 0.15.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


2. _Tympanidium spinosum_, n. sp.

Shell with twelve gates; the four lateral gates simple. Basal and mitral
gates of about equal size. Shell similar to that of the preceding species,
differing mainly in the different armature; the numerous spines, covering
the convex outside of the four vertical rings, are not leaf-shaped, but
conical, short, of very variable size, partly simple, partly irregularly
branched.

_Dimensions._--Length of the shell 0.08 (with spines 0.2), breadth 0.12.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.



{1004}Subgenus 2. _Tympanomma_, Haeckel.

_Definition._--Shell with sixteen gates (eight median gates, paired on both
sides of the sagittal ring, and eight lateral gates, paired on both sides
of the frontal ring). The four lateral gates of the two preceding species
(subgenus _Tympanura_) are bisected in _Tympanomma_ by the lateral parts of
an incomplete equatorial ring.


3. _Tympanidium binoctonum_, n. sp. (Pl. 94, fig. 18).

Shell with sixteen gates; the four lateral gates double, bisected by the
lateral parts of an incomplete equatorial ring. Basal gates nearly
rectangular, of the same breadth as the pentagonal mitral gates, but twice
as long. Equatorial outline of the shell (seen in fig. 18 from the apical
pole) octagonal. All rods of the shell thin, smooth.

_Dimensions._--Transverse axis of the shell 0.1, sagittal axis 0.06.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


4. _Tympanidium barbadense_, Haeckel.

  "Hollow cylinder," &c., Bury, 1862, Polycystins of Barbados, pl. xvi.
  fig. 1.

Shell with sixteen gates; the four lateral gates double, bisected by an
incomplete equatorial ring. Basal gates kidney-shaped, of the same breadth
as the circular mitral gates, but twice as long. Equatorial outline of the
shell elliptical. All rods of the shell thin, smooth.

_Dimensions._--Transverse axis of the shell 0.12, sagittal axis 0.08.

_Habitat._--Fossil in South Naparima, Trinidad, Barbados.


5. _Tympanidium staurocircum_, n. sp.

Shell with sixteen gates; the four lateral gates double, bisected by an
incomplete equatorial ring. Basal and mitral gates of the shell of about
equal size, roundish.  Equatorial outline of the shell violin-shaped, with
a sagittal constriction. All rods of the shell armed with short irregular
spines.

_Dimensions._--Transverse axis of the shell 0.12, sagittal axis 0.06.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



Subfamily 2. PARATYMPANIDA, Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Tympanida# with two fenestrated horizontal rings, which are
connected by a variable number of vertical rods or columellæ. The shell
therefore becomes more completely latticed than in the other Tympanida, and
approaches that of the #Spyroidea#.



{1005}Genus 432. _Paratympanum_,[51] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Tympanida# with two latticed horizontal rings, connected by
numerous descending and diverging columellæ; mitral ring smaller than the
basal ring.

The genus _Paratympanum_ and the following nearly allied _Lithotympanum_
form together the small subfamily of Paratympanida, distinguished from the
other Tympanida by the fenestration of the two parallel horizontal rings.
These rings in _Lithotympanum_ are both equal, whilst in _Paratympanum_,
the basal ring is larger than the mitral ring; therefore the connecting
rods or columellæ are in the former parallel and vertical, in the latter
divergent and descending. Two opposite ones of these columellæ are parts of
the primary sagittal ring, two others are parts of the lateral or frontal
ring, whilst the remainder are afterwards intercalated. _Paratympanum_ may
be derived from _Dystympanium_ by fenestration of the basal ring.


1. _Paratympanum hexastylum_, n. sp.

Six divergent columellæ, about as long as the diameter of the hexagonal
mitral ring, connect it with the larger hexagonal basal ring. Lattice of
the mitral ring hemispherical, with six roundish pores, surrounding a
central apical horn. Lattice of the basal ring with one large central pore,
surrounded by numerous peripheral pores. Rings and rods smooth, without
spines.

_Dimensions._--Length of the shell 0.07; breadth of the mitral ring 0.06,
of the basal ring 0.09.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Paratympanum octostylum_, n. sp. (Pl. 94, fig. 14).

Eight divergent columellæ, about as long as the diameter of the octagonal
mitral ring, connect it with the larger circular basal ring, and bear at
each end a divergent, strong, conical spine. Lattice-plate of both rings
slightly convex, with numerous subregular circular pores, smooth, without
surface spines.

_Dimensions._--Breadth of the mitral ring 0.06, of the basal ring 0.09.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Paratympanum decastylum_, n. sp.

Ten divergent columellæ, only half as long as the diameter of the decagonal
mitral ring, connect it with the larger circular basal ring. Lattice-plate
of the mitral ring nearly hemispherical of the basal ring flat, both with
numerous irregular roundish pores and scattered spines. Margin of both
rings spiny.

_Dimensions._--Breadth of the mitral ring 0.08, of the basal ring 0.1.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



{1006}Genus 433. _Lithotympanum_,[52] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Tympanida# with two latticed horizontal rings, connected by
numerous parallel and vertical columellæ; mitral and basal rings of equal
size.

The genus _Lithotympanum_ has the form of a cylindrical drum, the two
fundamental faces of which (the mitral and basal gates) are closed by
lattice-work. Both horizontal rings are equal, whilst in the preceding
_Paratympanum_ the basal gate is larger than the mitral. It may be derived
from the latter by equalisation of these two rings, or directly from
_Dystympanium_ by fenestration of the basal ring.


1. _Lithotympanum tuberosum_, n. sp. (Pl. 83, fig. 1).

Both lattice-plates slightly convex; the mitral plate with six larger
marginal pores and one central pore separated by numerous smaller pores;
the basal plate with seven large pores only (one central and six
peripheral). Surface and margin of the plates uneven, with roundish
prominent dimpled tubercles. Both rings connected by ten to twelve simple
cylindrical vertical columellæ.

_Dimensions._--Length of the shell 0.13, breadth 0.1.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Lithotympanum spinosum_, n. sp.

Both lattice-plates flat, with numerous irregular roundish pores of
variable size. Surface thorny. Margin with numerous irregular spines,
directed upwards on the mitral, downwards on the basal plate. Both rings
connected by eight simple cylindrical vertical columellæ.

_Dimensions._--Length of the shell 0.12, breadth 0.08.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.



Subfamily 3. DYSTYMPANIDA, Haeckel.

_Definition._--#Tympanida# with fenestrated mitral ring and simple open
basal ring; both horizontal rings connected by numerous vertical or
divergent columellæ.



Genus 434. _Dystympanium_,[53] n. gen.

_Definition._--#Tympanida# with two horizontal rings, connected by numerous
(six to eight or more) divergent columellæ. The upper mitral ring is
smaller and latticed, the lower basal ring larger and open.

{1007}The genus _Dystympanium_, representing a peculiar subfamily, differs
from all other Tympanida in the different shape of the two parallel
horizontal rings. The upper or mitral ring is closed by a lattice-plate (as
in _Paratympanum_), the lower or basal ring is simple and open (as in
_Eutympanium_). _Dystympanium_ may therefore be regarded as an intermediate
form between these two genera, and may perhaps be derived from
_Paratympanum_ by loss of the lower lattice-plate.


1. _Dystympanium dictyocha_, n. sp. (Pl. 94, figs. 15, 16).

Basal ring circular, with eighteen to twenty short conical divergent
spines. Mitral ring about two-thirds as broad, hexagonal, with six
ascending spines on the six corners. The latter are connected with the
former by six simple, straight, obliquely descending columellæ, about as
long as the diameter of the mitral ring. Mitral lattice-plate slightly
convex, with seven roundish pores (six peripheral pores around a central
pore).

_Dimensions._--Diameter of the basal ring 0.09, mitral ring 0.06; length of
the columellæ 0.05.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.


2. _Dystympanium distephanus_, n. sp.

Basal ring hexagonal, with six larger spines at the six corners, and
numerous smaller ones between them. Mitral ring half as broad as the basal
ring, also with six angular spines. The latter are connected with the
former by six divergent curved columellæ, about as long as the diameter of
the basal ring. Mitral lattice-plate flat, with irregular roundish pores.

_Dimensions._--Diameter of the basal ring 0.1, mitral ring 0.05; length of
the columellæ 0.09.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.


3. _Dystympanium medusa_, n. sp.

Basal ring circular, with eight larger and numerous smaller divergent
spines. Mitral ring two-thirds as broad as the basal ring, octagonal, with
eight conical ascending spines on the eight corners. The latter are
connected with the former by eight divergent, curved columellæ, as long as
the diameter of the mitral ring. Mitral lattice-plate nearly hemispherical,
with nine circular pores (eight peripheral pores around one central pore).

_Dimensions._--Diameter of the basal ring 0.12, mitral ring 0.08; length of
the columellæ 0.09.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.



Subfamily 4. EUTYMPANIDA, Haeckel.

_Definition._--#Tympanida# with two simple horizontal rings, which are
connected by a variable number of vertical rods or columellæ. Therefore the
shell exhibits a large simple mitral gate on the upper, and a large simple
basal gate on the lower side; between the two a variable number of lateral
gates.



{1008}Genus 435. _Parastephanus_, Haeckel, 1881, Prodromus, p. 446.

_Definition._--#Tympanida# with two simple horizontal rings, connected by
two vertical columellæ.

The genus _Parastephanus_ is the simplest among the Eutympanida, and
exhibits only two vertical rods or columellæ, which connect the two
parallel horizontal rings. One of these latter must be regarded as the
mitral or superior ring, the other as the basal or inferior ring; whilst
the two parallel columellæ, connecting both, are the remaining vertical
parts of the sagittal ring, the upper and lower parts of which are lost. By
loss of the latter _Parastephanus_ has probably been derived from
_Protympanium_.


1. _Parastephanus circularis_, n. sp.

Two horizontal rings smooth, circular, of equal size, connected by two
curved smooth columellæ, which are somewhat shorter than the diameter of
the rings.

_Dimensions._--Diameter of the rings 0.08, length of the columellæ 0.06.

_Habitat._--Central Pacific, Station 263, depth 2650 fathoms.


2. _Parastephanus quadrispinus_, n. sp. (Pl. 93, fig. 21).

Two horizontal rings smooth, elliptical or nearly circular, of equal size,
connected by two vertical, slightly curved columellæ, which are about as
long as the radius of the rings. Each ring bears two simple lateral spines,
which in the mitral ring are curved downwards, in the basal ring upwards,
possibly the last remains of a reduced frontal ring.

_Dimensions._--Diameter of the rings 0.09, length of the columellæ 0.05.

_Habitat._--North Pacific, Station 236, surface.


3. _Parastephanus asymmetricus_, n. sp. (Pl. 82, fig. 10).

Two horizontal rings thorny, of equal size, irregularly ovate or nearly
semicircular, and of somewhat asymmetrical form. The two connecting
parallel columellæ are straight, cylindrical, about as long as the diameter
of the rings. The peculiar asymmetry in the form of the rings raises the
possibility that the two columellæ in this species are the remaining parts
of a frontal ring, and that the sagittal ring has altogether disappeared.
In this case the convex half of both rings would be the ventral, the
straight half the dorsal part.

_Dimensions._--Diameter of the rings 0.1, length of the columellæ 0.08.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


{1009}4. _Parastephanus dispar_, n. sp.

Two horizontal rings elliptical, thorny, of different sizes, the basal ring
one and a half times as broad as the mitral ring. The two connecting
columellæ are curved, somewhat longer than the diameter of the mitral ring.

_Dimensions._--Diameter of the basal ring 0.09, mitral 0.06; length of the
columellæ 0.07.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.



Genus 436. _Prismatium_,[54] Haeckel, 1862, Monogr. d. Radiol., p. 270.

_Definition._--#Tympanida# with two simple horizontal rings, connected by
three vertical columellæ.

The genus _Prismatium_ was hitherto the only known form of the Tympanida,
and the only species described in 1862 in my Monograph was _Prismatium
tripleurum_ (_loc. cit._, p. 270, pl. iv. fig. 6). A new species from the
Challenger collection (Pl. 93, fig. 22), _Prismatium tripodium_, explains
the true structure of this remarkable genus. The skeleton is composed of
nine siliceous rods, corresponding to the edges of a trilateral prism. Six
of these are horizontal, and enclose the two parallel triangular horizontal
gates, the superior of which is formed by the mitral or coryphal, and the
inferior by the basal or cortinar ring. The three other rods are vertical
and nearly parallel, and connect (as lateral edges of the prism) the
corresponding corners of the two parallel horizontal triangles. Two of
these vertical columellæ, together with the two horizontal parallel rods
connecting them, represent the complete frontal ring, whilst the third
vertical columella is the posterior half of the sagittal ring, the other
parts of which are lost.


1. _Prismatium tripodium_, n. sp. (Pl. 93, fig. 22).

Mitral ring triangular, somewhat smaller than the triangular basal ring,
both connected at the corners by three vertical, slightly curved columellæ.
From the six corners arise six radial spines of different size and form;
the two paired spines of the mitral ring are simple and very small, whilst
those of the basal ring are three times as long and bear a lateral branch.
The odd spine of the third corner is on both rings larger, and
distinguished by some thorns. This difference seems to indicate that these
two odd spines correspond to the apical horn and the caudal foot of
_Cortina_, and the columella between them is the rest of the reduced
sagittal ring. In this case the quadrangular vertical ring, which is
composed of the two paired columellæ and the two connecting horizontal
rods, would be probably the frontal ring.

_Dimensions._--Length of the shell 0.09, breadth 0.07.

_Habitat._--Equatorial Atlantic, Station 347, surface.


{1010}2. _Prismatium tripleurum_, Haeckel.

  _Prismatium tripleurum,_ Haeckel, 1862, Monogr. d. Radiol., p. 270, Taf.
  iv. fig. 6.

  _Acanthodesmia prismatium_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
  d. Wiss. Berlin, p. 799.

Mitral and basal rings of equal size, equilateral triangular, both
connected at the corners by three vertical equal columellæ. From the six
corners arise six short, equal, conical radial spines. The nine rods of the
shell correspond to the nine edges of a triangular equilateral prism.

_Dimensions._--Length of the shell 0.044, breadth 0.032.

_Habitat._--Mediterranean (Messina), surface.



Genus 437. _Pseudocubus_,[55] n. gen.

_Definition._--#Tympanida# with two simple horizontal rings of different
sizes, connected by four divergent columellæ.

The genus _Pseudocubus_ exhibits the characteristic form of an obelisk, or
a truncated four-sided pyramid. The four edges of this obelisk, or the four
"columellæ," are the remaining parts of the two incomplete vertical rings;
two opposite edges are the dorsal and ventral rod of the sagittal ring; the
two alternate edges between these are the lateral rods of the frontal ring.
The two horizontal rings, which become connected by the four divergent
columellæ, are the smaller mitral ring and the larger basal ring; both are
either square or nearly circular.


1. _Pseudocubus obeliscus_, n. sp. (Pl. 94, fig. 11).

Mitral ring square, with circular gate and two divergent simple spines on
each corner. Basal ring twice as broad, square, with four convex sides and
one simple spine on each corner. Four columellæ straight. All twelve rods
with three smooth edges.

_Dimensions._--Breadth of the mitral ring 0.02, of the basal ring 0.05.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Pseudocubus octostylus_, n. sp.

Mitral ring square, with one stout pyramidal spine on each corner. Basal
ring twice as broad, square, also with a single strong spine on each
corner. Four columellæ straight. All twelve rods with three smooth edges.

_Dimensions._--Breadth of the mitral ring 0.04, of the basal ring 0.08.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


{1011}3. _Pseudocubus hexapylus_, n. sp. (Pl. 94, fig. 12).

Mitral ring circular, two-thirds as broad as the subcircular, or nearly
square, basal ring; both rings with a simple spine on the two sagittal
corners (dorsal and ventral), with a forked or branched larger spine on the
two lateral corners (right and left). All twelve rods more or less curved
and thorny.

_Dimensions._--Breadth of the mitral ring 0.07, of the basal ring 0.1.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 438. _Lithocubus_,[56] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Tympanida# with two simple horizontal rings of equal size,
connected by four parallel vertical columellæ.

The genus _Lithocubus_ is very remarkable for the regular cubical form of
the skeleton, which is composed of twelve siliceous rods, corresponding to
the twelve edges of a cube. Eight of these are horizontal, and enclose the
two parallel square horizontal gates, the superior mitral and the inferior
basal gate. The four other rods are vertical, parallel, and connect (as
lateral edges of the cube) the corresponding corners of the two horizontal
squares. Two opposite ones of these four vertical columellæ are the
remaining halves of the incomplete sagittal ring; the two alternate are the
remaining halves of the incomplete frontal ring. The four lateral gates
between these four columellæ are also square or rectangular, and either of
the same size as the two horizontal gates, or somewhat larger. _Lithocubus_
may be derived from _Acrocubus_ by reduction of the coryphal and the basal
part of the primary sagittal ring, the only remaining parts of which are
the anterior and the posterior columellæ.


1. _Lithocubus geometricus_, n. sp. (Pl. 94, fig. 13).

The twelve rods, corresponding to the edges of the geometrical cube, are
straight and smooth; the eight corners provided with a small conical thorn.
The shell exhibits six equal square sides, and represents therefore exactly
the geometrical form of a cube.

_Dimensions._--Diameter of the cube 0.05; thickness of the bars 0.008.

_Habitat._--Tropical Pacific, Station 224, depth 1850 fathoms.


2. _Lithocubus octacanthus_, n. sp.

The twelve rods of the cubical shell are slightly curved, convex, smooth,
as in the similar preceding species. It differs from that in the
development of eight slender radial spines, arising from the eight corners
of the geometrical cube, from two to three times as long as its diameter,
and lying opposite in pairs in its diagonals.

_Dimensions._--Diameter of the cube 0.06; length of the spines 0.15.

_Habitat._--North Atlantic, Canary Islands, surface.


{1012}3. _Lithocubus vinculatus_, Haeckel.

  _Acanthodesmia vinculata_, J. Müller, 1856 (_partim_), Abhandl. d. k.
  Akad. d. Wiss. Berlin, Taf. i. fig. 7 (not 4-6).

The twelve rods of the cubical shell are curved and armed with scattered,
simple, short spines. The figure 7 of Johannes Müller (_loc. cit._)
corresponds exactly to the Mediterranean form observed by me at Portofino,
and is quite different from his true _Acanthodesmia vinculata_ (_loc.
cit._, figs. 4-6), so that I have no doubt he did observe these two
different species (compare above, p. 975).

_Dimensions._--Diameter of the cube 0.07; length of the spines 0.02.

_Habitat._--Mediterranean (Nice, Portofino).


4. _Lithocubus astragalus_, n. sp. (Pl. 82, fig. 12).

The twelve rods of the cubical shell are stout and slightly curved, armed
with numerous, simple, and irregularly branched spines. Eight larger
spines, branched like a deer's antler, arise from the eight corners of the
cube.

_Dimensions._--Diameter of the cube 0.1 to 0.12; length of the corner
spines 0.05 to 0.08.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 439. _Circotympanum_,[57] n. gen.

_Definition._--#Tympanida# with two simple different horizontal rings,
connected by numerous (six to eight or more) divergent columellæ.

The genus _Circotympanum_ comprises those Tympanida in which two simple
horizontal rings of different size (an upper smaller "mitral ring," and a
lower larger "basal ring") are connected by a variable number of divergent
rods or columellæ (at least six or eight). _Circotympanum_ is probably
derived from _Tympaniscus_ or _Tympanidium_ by partial reduction of the
sagittal ring, the upper (apical) and lower (basal) part of which is lost.
The geometrical fundamental form is a truncated pyramid with six to eight
or more edges.


1. _Circotympanum hexagonium_, n. sp.

Mitral and basal ring hexagonal, the latter twice as broad as the former,
each with a simple small spine on the six corners. Six columellæ nearly
straight, as long as the radius of the basal ring. All rods with three
prominent edges.

_Dimensions._--Breadth of the mitral ring 0.06, of the basal ring 0.11.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


{1013}2. _Circotympanum octogonium_, n. sp. (Pl. 94, fig. 17).

Mitral and basal rings octagonal, the latter one and a half times as broad
as the former. Eight columellæ slightly curved, thorny. The mitral ring
bears on each corner a short ascending spine, the basal ring a larger,
thorny, obliquely descending spine, which has some recurved thorns on the
upper edge. All rods more or less thorny.

_Dimensions._--Breadth of the mitral ring 0.06, of the basal ring 0.09.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Circotympanum decagonium_, n. sp.

Mitral and basal rings circular, the latter nearly twice as broad as the
former, both armed with scattered irregular thorns. Ten columellæ smooth,
curved.

_Dimensions._--Breadth of the mitral ring 0.07, of the basal ring 0.12.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.



Genus 440. _Eutympanium_,[58] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Tympanida# with two simple equal horizontal rings,
connected by numerous (six to eight or more) parallel and vertical
columellæ.

The genus _Eutympanium_ contains those Tympanida in which the drum-shaped
shell is composed of two simple, parallel and equal horizontal rings, and
numerous vertical and parallel rods or columellæ connecting them. The
number of the latter is at least six or eight. Two opposite of these must
be regarded as remaining vertical parts of the sagittal ring, two others as
parts of the frontal ring, whilst the other columellæ (between the former
and the latter) are secondary and intercalated. Therefore _Eutympanium_ may
be derived from _Tympanidium_ by reduction and loss of the apical and basal
parts of the sagittal ring.


1. _Eutympanium musicantum_, n. sp. (Pl. 83, fig. 2).

Eight parallel and vertical columellæ, simple, straight and smooth. Both
horizontal rings equal, circular, each armed with eight to twelve short
conical thorns.

_Dimensions._--Height of the shell 0.09, breadth 0.07.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


{1014}2. _Eutympanium octonarium_, n. sp.

Eight vertical columellæ slightly curved, thorny. Both horizontal rings
equal, octagonal, each armed with eight large, irregularly-branched spines,
which on the mitral ring are directed obliquely upwards, on the basal ring
downwards.

_Dimensions._--Height of the shell 0.12, breadth 0.1.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Eutympanium coronarium_, n. sp.

Eight thorny columellæ, obliquely descending and curved like a bow,
divergent in the upper part, convergent in the lower. Basal ring circular,
mitral ring octagonal. Both horizontal rings armed with eight stout thorny
spines, which on the mitral ring are smaller and directed obliquely
upwards, on the basal ring larger and directed downwards, each with a
recurved hook.

_Dimensions._--Height of the shell 0.08, breadth 0.06.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


4. _Eutympanium militare_, n. sp. (Pl. 82, fig. 11).

Ten parallel and vertical columellæ straight and smooth, cylindrical. Both
horizontal rings equal, circular, armed with numerous short conical spines,
divergent in all directions. Ten to twenty spines on each ring larger than
the others.

_Dimensions._--Height of the shell 0.1, breadth, 0.08.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


5. _Eutympanium dodecarium_, n. sp.

Twelve vertical columellæ, slightly curved, smooth. Mitral and basal rings
circular, both horizontal rings armed with twelve stout,
irregularly-branched spines, which are prolongations of the columellæ, and
on the mitral ring directed upwards, on the basal ring downwards.

_Dimensions._--Height of the shell 0.13, breadth 0.1.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


{1015}----


Order VI. CYRTELLARIA, Haeckel, 1881.

_Definition_.--NASSELLARIA with a complete lattice-shell enveloping the
central capsule.



Suborder I. SPYROIDEA, Haeckel.

  _Spyridina_, Ehrenberg (_pro parte_), 1847, Monatsber. d. k. preuss.
      Akad. d. Wiss. Berlin, p. 54.
  _Zygocyrtida_, Haeckel, 1862, Monogr. d. Radiol., p. 291.
  _Zygocyrtida_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p.
      501.
  _Acanthodesmida_, R. Hertwig, 1879, Organismus der Radiol., p. 68.
  _Spyrida_ vel _Spyroidea_, Haeckel, 1881, Prodromus, p. 440.

_Definition._--NASSELLARIA with a complete lattice-shell, exhibiting
constantly a bilocular cephalis with a sagittal constriction.

The suborder #Spyroidea#, and the two following closely allied suborders,
#Botryodea# and #Cyrtoidea#, represent together that large group of
Radiolaria which I first described in my Monograph (1862, pp. 272, 280) as
the family Cyrtida, but afterwards as a separate order (or sublegion) under
the name #Cyrtellaria# (1883, Jena. Sitzungsber., Feb. 16, p. 18). This
group comprises all those MONOPYLEA or NASSELLARIA which possess a complete
lattice-shell, whilst the preceding #Plectellaria# never develop a perfect
fenestrated shell enveloping the central capsule. The #Spyroidea# differ
from the other #Cyrtellaria# (#Botryodea# and #Cyrtoidea#) in the bilocular
shape of the cephalis, which is bisected by the sagittal ring and a
corresponding longitudinal constriction into two symmetrical halves.

The #Spyroidea# appear in the first system of Polycystina of Ehrenberg
(1847, _loc. cit._, pp. 53, 54) as the fourth of his seven families, under
the name Spyridina, with the following definition:--"Testæ nucleo destitutæ
(associatæ et coalitæ); cellulæ binæ clathratæ, nucis forma amplæ,
strictura longitudinali levius discretæ." Ehrenberg united them with his
"Polycystina composita or SPUMELLARIA" and separated them from the closely
allied "Polycystina solitaria or NASSELLARIA." He distinguished among them
five genera, two of which have no external appendages (_Dictyospyris_ and
_Pleurospyris_), whilst the other three possess spiny or lamellar
appendages (_Ceratospyris_, _Cladospyris_, and _Petalospyris_). These five
genera and the accompanying definitions were also repeated in the same
terms in the last system of Ehrenberg (1875, _loc. cit._, p. 157). In my
Monograph (1862, pp. 280, 291) the #Spyroidea# are enumerated as a
{1016}subfamily of the Cyrtida, under the name Zygocyrtida, with the
following definition:--"Lattice-shell divided by an annular sagittal
longitudinal constriction into two neighbouring equal joints or chambers."
I adopted at that time the above five genera of Ehrenberg, only eight
species of which were known.

Richard Hertwig gave in 1879 the first accurate description of the central
capsule of the #Spyroidea#, and demonstrated that they possess the same
characteristic structure of the capsule, with a porochora and a podoconus,
that is common to all MONOPYLEA. He separated the Zygocyrtida from the
other Cyrtida, and united them with the #Stephoidea# (_Lithocircus_) in the
family Acanthodesmida. In my Prodromus (1881, p. 449) I adopted that
division and put the "Spyrida or #Spyroidea#" as a separate family between
the #Cyrtoidea# and #Stephoidea#. I there gave the following
definition:--"_Monopylaria gemina_, testa silicea clathrata gemina, cameris
binis juxta compositis, annulo verticali sagittali contiguis, capsula
centrali a testa inclusa. Promorpha dipleura vel bilaterali, dextro et
sinistro antimero symmetricis, plano sagittali annuloque separatis. Polum
superiorem axis verticalis vel principalis plerumque spina apicalis (vel
occipitalis) occupat, polum inferiorem ostium clathratum (poris tribus aut
quatuor aut pluribus) et spina caudalis (posterior). Ad dextram et
sinistram duæ spinæ laterales distant. Ab hac forma tripoda (Monocyrtida
triradiata acuta cum annulo mediano) diversæ Spyridum formæ derivandæ
sunt." I there divided the Spyrida into seven subfamilies and forty-eight
genera. Bütschli in 1882 published accurate researches on the Zygocyrtida
in his Beiträge zur Kenntniss der Radiolarien-Skelete, insbesondere der der
Cyrtida (Zeitschr. f. wiss. Zool., vol. xxxvi. p. 501, Taf. xxxii.). He
gave a very exact anatomical description of the skeleton of several fossil
#Spyroidea# of Barbados, and pointed out their close affinity to the
Acanthodesmida on the one hand, and to the Cyrtida on the other. Regarding
their phylogenetical relation, he supposed that the Zygocyrtida have
descended from the Acanthodesmida (our #Stephoidea#) and are the ancestors
of all other Cyrtida. The best part of this valuable paper of Bütschli is
his exact description of the sagittal ring and its apophyses, producing the
basal plate; and the general conception thus derived of the essential parts
of the skeleton in all MONOPYLEA, bearing a sagittal ring. But his general
conclusions were partly erroneous, since the fossil #Spyroidea# and
#Cyrtoidea# of Barbados, upon which they were founded, contain only the
minority of genera of the large group; and many important and typical forms
remained unknown to him.

The numerous new genera discovered in the rich collection of the
Challenger, and mainly in the wonderful Radiolarian ooze of the Central
Pacific (Stations 263 to 274) throw a new light upon the complicated
affinities of the whole group, and manifest a far greater richness in
developmental variations and admirable morphological productions than
Bütschli could suppose. The following description, however, must remain
very incomplete, since the exact and thorough study of all individual
forms, in the same manner as {1017}Bütschli had done in the case of a small
number of species, would require several years. I can therefore only give
the basis of further researches.

In the majority of #Spyroidea# the three essential elements of the
Nassellarian skeleton are easily recognisable, viz.:--A, the vertical
sagittal ring of the #Stephoidea#; B, the basal tripod of the #Plectoidea#,
and C, the latticed cephalis of the #Cyrtellaria#. These three elements are
constantly so combined that the primary sagittal ring bisects the cavity of
the lattice-shell and produces an external, longitudinal, more or less
distinct constriction, separating the lateral inflated halves of the
bilocular cephalis; while the three divergent feet of the basal tripod
descend from the cortinar or basal plate of the cephalis. The number of the
feet is often augmented; they are rarely wanting (probably reduced). The
sagittal ring is constantly present, though its relation to the shell-wall
exhibits many modifications. The bilocular form of the fenestrated
cephalis, with its sagittal constriction, is characteristic of all true
#Spyroidea#, and separates them from the #Botryodea# (with multilobate
cephalis) on the one hand, and from the #Cyrtoidea# (with simple cephalis)
on the other. There are, however, some intermediate forms between these
three suborders of #Cyrtellaria#, which show a direct transition to one
another. Almost constantly the length of the three dimensive axes in the
cephalis of the #Spyroidea# is so different that the lateral or frontal
axis is the longest, the sagittal or dorso-ventral axis the shortest, and
the principal or longitudinal axis intermediate between them. As in all
dipleuric or bilaterally symmetrical forms, the two poles of the frontal
axis are equal, whilst the two poles of the sagittal and of the principal
axis are more or less different. In only a few forms of #Spyroidea# these
differences are difficult to make out; usually the dorsal side is
distinctly different from the ventral, and the apical side from the basal.
A perfect knowledge of the dipleuric shell requires therefore accurate
observation from all six sides.

The suborder of #Spyroidea# is here divided into four different families.
In the first and original family, the Zygospyrida, the shell is represented
by the bilocular cephalis only. The second family, Tholospyrida, is
distinguished by a fenestrated cupola or galea, a hemispherical or conical
dome, arising from the upper or coryphal face of the cephalis. In the third
family, Phormospyrida, a thorax is developed, or a fenestrated basal
chamber, arising from the lower or basal face of the cephalis. The fourth
family, Androspyrida, combines the characters of the second and the third
family, a galea arising from the upper and a thorax from the lower face of
the cephalis.

The bilocular cephalis, as the most important and constant part of the
skeleton in all #Spyroidea#, requires a further general consideration. Its
lattice-work, very variable in the numerous species, is usually more or
less different on the six sides of the nut-shaped shell. Its most important
part is the horizontal basal plate or lower face, and the sagittal ring
arising from it in the vertical median plane. This part of the shell
corresponds exactly to the skeleton of the Semantida, and exhibits the same
modifications {1018}as in that family; it is therefore probable that the
majority of the #Spyroidea# (if not the whole group) have been derived
directly from the Semantida by further development of network from the
fenestrated ring of _Clathrocircus_. Whilst in this latter Semantid the two
lateral sides of the central capsule remain naked, in the #Spyroidea# they
become enclosed and covered by lattice-work, which arises on the right and
left from the ring. In some forms, however, as in the _Ceratospyris
acuminata_ of Hertwig, and in my Perispyrida, the frontal ring also of the
Coronida and the mitral ring of the Tympanida appear as the initial parts
of a complete latticed cephalis.

The basal plate of the cephalis, or the "cortinar plate," the
"Basal-Scheibe" of Bütschli, has constantly, according to this author, two
pairs of pores, an anterior smaller pair of jugular pores (the pores I of
Bütschli) and a posterior larger pair of cardinal pores (the pores II in
his description) (compare Pl. 95, figs. 3, 6). This applies to the majority
of #Spyroidea#, but by no means to the whole group. We find basal plates
with two pores only (Pl. 95, fig. 1), with three pores (figs. 2, 5), with
six pores (figs. 4, 7), with nine pores (Pl. 87, fig. 2), &c. The forms
with two basal pores may be derived directly from _Semantis_ (Pl. 92, figs.
1, 2); the common forms with four pores from _Semantrum_ (figs. 3-5); the
rarer forms with six pores from _Semantidium_ (figs. 6, 7); and the forms
with three pores from _Cortiniscus_, &c. In this as well as in other
respects the variety of different forms and of developmental variations is
far greater than Bütschli (1882, _loc. cit._) supposed. The bars between
the pores of the basal plate possess the same value and the same names as
in the Semantida (compare above, p. 954).

The coryphal plate of the cephalis, its upper or apical lattice-plate, does
not exhibit such important differences as the opposite basal plate, is far
less variable, and is usually pierced by numerous, smaller pores. Some
larger pores lie, often in pairs, on the right and left side of the
sagittal constriction, and have in some groups a regular form and
disposition. Either in the middle of the coryphal plate, or (usually)
nearer to its dorsal margin, there arises in majority of #Spyroidea# an
apical horn, directed either vertically or more or less obliquely
backwards. In many #Spyroidea# three horns are developed in the coryphal
plate, the odd middle apical horn and two paired frontal or lateral horns
arising on each side of the latter and directed more forwards (Pl. 84,
figs. 9-12). Sometimes the apical horn disappears, while the two frontal
horns remain (Pl. 95, fig. 12).

The anterior or ventral plate of the cephalis (the "Hinterseite" of
Bütschli), and the posterior or dorsal side (the "Vorderseite" of that
author), exhibit in the majority of #Spyroidea# more or less marked
differences in the number, form, and disposition of their pores, which
require a far more accurate description than is here possible. Usually the
sagittal constriction of these two plates, produced by the primary vertical
ring, is deeper and sharper in the middle of the ventral than in that of
the dorsal plate. On both sides of the ring there appear in each plate
usually two or three pairs of larger pores, whilst numerous smaller pores
are situated towards the lateral sides. We may {1019}distinguish the large
pores of the ventral plate as facial pores (upper orbital, middle nasal,
and lower maxillary pores), and the opposite large pores of the dorsal
plate as occipital pores (upper epoccipital, middle mesoccipital, and lower
suboccipital pores). A closer comparison of these pores, and of the
separating bars in the numerous #Spyroidea#, may show a regularity of
development similar to that offered by the homologies of the parts in the
skeleton of the Echinodermata, or of the bones in the skull of the
Vertebrata.

The two convex lateral plates of the cephalis, or the right and left sides,
both symmetrically equal, do not exhibit the same regularity in the shape,
number, and disposition of the pores that the four other sides do. Usually
their pores are much smaller and more numerous. In very few forms only a
distinct frontal ring is visible (corresponding to that of the Coronida),
and in this case the lateral pores are sometimes disposed symmetrically on
both sides of this ring. These #Spyroidea# may have arisen directly from
corresponding forms of Coronida.

The sagittal ring (or the primary vertical ring) inherited from the
Stephanida and Semantida, shows in the #Spyroidea# great variety in its
form and in its relation to the cephalis. These variations are far greater
than Bütschli (1882, _loc. cit._) supposed. We may distinguish the
following six principal cases:--A. The ring lies completely in the wall of
the cephalis, and causes a deep sagittal constriction in it. In this case
the lower part or basal segment of the ring separates the basal pores into
pairs; its anterior part or ventral rod the facial pores; its upper part or
coryphal rod the apical pores; and its posterior part or dorsal rod the
occipital pores. No part of the ring is free in the shell-cavity. B. The
greater part of the ring lies enclosed in the shell-wall; only its dorsal
rod arises free in the shell-cavity and ascends vertically or obliquely to
the apex, where it is usually prolonged into the apical horn. This seems to
be the most common case. C. The coryphal and the basal part of the ring lie
enclosed in the shell-wall, with its dorsal and ventral rod free in the
shell-cavity; the dorsal rod ascends vertically to the apex, the ventral
rod obliquely upwards to the upper part of the facial plate (the nasal or
orbital region). This case, regarded by Bütschli as the usual one, is far
less common than he supposed. D. The greater part of the ring lies free in
the shell-cavity, its basal rod only is enclosed in the shell-wall, and
separates the right from the left group of the cortinar pores. This case
seems to be rarer than the preceding. E. The whole ring lies free in the
shell-cavity, and is connected with the sagittal constriction of the
shell-wall by numerous short radial beams. The distance of the shell-wall
from the enclosed ring is usually least on the basal rod, and greatest on
the dorsal rod. F. The whole ring lies free in the shell-cavity (as in the
preceding case), and is connected by numerous short radial beams with a
secondary larger, concentric sagittal ring, which is developed in the
longitudinal constriction of the shell-wall.

{1020}Comparing these six principal cases, in respect of the relation of
the primary sagittal ring to the cephalis of the #Spyroidea#, we may
suppose that they represent together a continuous phylogenetical series of
which the first (A) is the original, and the last (F) the latest case; and
that the true cause of the various changes is a successive separation of
the ring, which becomes more and more free and independent from the
lattice-plate of the cephalis. Since the intimate study of the structure of
the cephalis in many #Spyroidea# is very difficult, it requires further
accurate observations (from all six sides of the shell). There are also
some other more difficult complications of its structure, which cannot be
solved without exact study and extended comparison.

Of peculiar importance for the differentiation of the numerous genera of
the #Spyroidea# are the basal feet or the descending and diverging
apophyses, which are developed from the base of their cephalis. In general
they exhibit the same typical shape which we find in the #Plectellaria# as
well as in the #Cyrtoidea#, and which we regard therefore as an important
common character of the majority of NASSELLARIA. We may therefore
distinguish here also the three primary, and the other ones as secondary
feet. The three primary feet, or the "cortinar feet," are the same that we
found in the Plagonida and Plectanida, in _Cortina_ and _Cortiniscus_ among
the #Stephoidea#, and in the majority of #Cyrtoidea#. They also reappear in
the same characteristic disposition and connection with the basal plate of
the cephalis, in the majority of #Spyroidea#. The odd caudal foot (_c_) is
the lower prolongation of the dorsal rod of the sagittal ring, which is
prolonged upwards into the apical horn. The two paired pectoral feet,
however (_p'_, _p''_), are the descending prolongations of the coracal rods
(_e_) which separate the jugular pores (_i_) from the cardinal pores (_k_)
of the cortinar plate (compare Pl. 95, figs. 2-6).

The three cortinar feet are nearly equally developed in the majority of
#Spyroidea# (compare Pls. 84, 89). But often the odd caudal foot exhibits a
different shape from that of the two paired pectoral feet, and in many
genera of the group it becomes more or less rudimentary. It has quite
disappeared in the subfamily Dipospyrida (Pl. 85); here the two pectoral
feet only are developed (often excessively), and are usually opposite in
the frontal plane. Such dipodal forms, very common in the #Spyroidea#, are
never found in the #Cyrtoidea#.

The secondary feet, which we contrast with the three primary feet as later
productions, exhibit great variations in number and development. Very
frequently three interradial secondary feet become developed, alternating
with the three primary cortinar or perradial feet, and opposed to them in
pairs (Pl. 95, figs. 7, 8). In these hexapodal #Spyroidea# (or Hexaspyrida)
an odd anterior or sternal foot (_z_) is opposite to the odd caudal foot,
and two paired posterior or tergal feet (_t'_, _t''_) to the two pectoral
feet. When the sternal foot becomes rudimentary or lost, pentapodal forms
arise (Pentaspyrida, Pl. 95, figs. 9-11), and when the two odd feet (caudal
and sternal) disappear, tetrapodal forms arise with two pairs of feet
(Therospyrida, Pl. 89, figs. 5, 6). The latter differ from {1021}those
quadrupedal forms in which two opposite sagittal feet (the caudal and
sternal) alternate in the form of a cross with two paired lateral or
pectoral feet (Tetraspyrida, Pl. 53, figs. 19, 20). In many #Spyroidea# the
number of basal feet is greatly increased, and they form a regular radial
corona around the basal plate, like a circle of tentacles (Polyspyrida, Pl.
87). In this latter case the feet are usually flat and lamellar, whilst in
the other groups they exhibit a very variable form, as is seen in Pls.
83-89.

The _Central Capsule_ of the #Spyroidea# has been accurately observed in
only a few genera, and requires a further exact examination regarding the
different modifications which occur in their different families. It is very
probable that these will agree with the well known modifications in the
corresponding groups of #Cyrtoidea#. The characteristic Monopylean
structure of the capsule (with porochora and podoconus) was first described
by Richard Hertwig in his _Ceratospyris acuminata_ (_loc. cit._, p. 72,
taf. vii. fig. 2). I found the same afterwards in many other forms. In the
Zygospyrida and Tholospyrida the central capsule seems to be usually
bilobate (bisected by the sagittal ring), and enclosed in the two chambers
of the cephalis. The two lobes of the capsule (right and left) are equal
and connected by a smaller middle part, which contains the transverse
elliptical nucleus and is enclosed by the sagittal ring; often each lobe
contains a large oil-globule. In some forms, however, three or four lobes
(sometimes perhaps more) are developed, which pierce the cortinar pores of
the basal plate and depend freely between the basal feet (Pl. 53, fig. 19).
In the Phormospyrida and Androspyrida the formation of such basal lobes
seems to be more frequent; they are here enclosed by the thorax. Usually
each lobe contains a large oil-globule. In _Nephrospyris_ (Pl. 90) and in
some similar genera the central capsule is violin-shaped, deeply bisected
by the sagittal ring; in each of the two lobes a series of oil-vesicles is
developed at both poles of the transverse axis (figs. 7, 10); the nucleus,
a transverse cylindrical body, is placed in the latter. In the periphery of
the voluminous calymma of this singular genus a large number of globular
cells are developed (figs. 7, 10), probably symbiotic xanthellæ. In some
forms of _Nephrospyris_ these xanthellæ are enclosed by a peculiar inflated
girdle, developed in the periphery of the kidney-shaped skeleton (Pl. 90,
figs. 1, 4-6).

_Synopsis of the Families of_ #Spyroidea#.

                                  {Cephalis without galea
  Shell without thorax; no second { (or apical cupola),   1. ZYGOSPYRIDA.
    shell-joint, developed from   {
    the base of the cephalis.     {Cephalis with a galea
                                  { (or apical cupola),   2. THOLOSPYRIDA.

                                  {Cephalis without galea
  Shell with a thorax, or a       { (or apical cupola),   3. PHORMOSPYRIDA.
    second shell-joint, developed {
    from the base of the cephalis.{Cephalis with a galea
                                  { (or apical cupola),   4. ANDROSPYRIDA.



{1022}Family LII. #ZYGOSPYRIDA#, n. fam. (Pls. 84-87).

_Definition._--#Spyroidea# without galea and thorax; the shell consisting
of the bilocular cephalis only and its apophyses.

The family Zygospyrida is by far the richest among the four families of
#Spyroidea#, the number of genera in the whole suborder amounting to
forty-five, in the former to twenty-eight; and the number of species in the
latter to two hundred and thirty-seven, in the former to one hundred and
seventy-two. The number of individuals also found in many species of
Zygospyrida is far greater than in any species of the three other families.
The shell of the Zygospyrida is represented by the bilocular cephalis only,
and never develops a galea (as in the Tholospyrida) nor a thorax (as in the
Phormospyrida and Androspyrida). The three latter families have therefore
been derived from the former as their common ancestral group.

The Zygospyrida are very similar and nearly related to the Monocyrtida, and
in both groups the cephalis alone represents the whole shell. Therefore in
1882, Bütschli, in the paper mentioned above (p. 1016), maintained the
opinion, that these two groups were identical. But there is this important
difference between them, that in the Zygospyrida (as in all #Spyroidea#)
the cephalis is bilocular, with a sagittal constriction, separating the
right and left chambers. In the Monocyrtida, however (as in all
#Cyrtoidea#), the cephalis is unilocular, forming a quite simple chamber
without sagittal constriction. Correspondingly the primary sagittal ring in
all Zygospyrida is well preserved and usually complete, while in the
Monocyrtida it is never complete, and often quite absent. Another
difference is indicated by the form of the central capsule, which in the
Zygospyrida is usually bilobed, and more developed in the frontal axis,
whilst in the Monocyrtida it is commonly ovate, and more developed in the
principal axis.

The important questions of the origin and phylogenetical relation of these
two similar groups of NASSELLARIA form a very complicated and difficult
problem, and we do not at present possess the means of solving it. It may
be that a part of the Monocyrtida has been derived from the Zygospyrida (as
Bütschli erroneously supposes for all), but the contrary is also possible.
A third possibility is the independent origin of both groups from the
Semantida. But we shall see afterwards, in the description of the
Monocyrtida, that a great part of this group may with greater probability
be derived from the #Plectoidea# than from the #Stephoidea#, and that
another part of them has probably been derived quite independently from the
Nassellida. Regarding the complicated relations of these similar groups,
mentioned above (pp. 892-894), it seems hopeless here to discuss further
their difficult affinities; but in any case it seems useful or even
necessary to separate the Monocyrtida from the Zygospyrida.

{1023}The cephalis of the Zygospyrida possesses all the characteristic
features which we have described above as belonging to the #Spyroidea# in
general (p. 1017), and a survey of the Pls. 84-87 exhibits the most
important modifications of its shape (compare also Pl. 95, figs. 1-13).
Therefore we may avoid useless repetitions by referring to the description
given above. We will only point out that the bilocular character of the
cephalis (in opposition to the simple cephalis of the Monocyrtida) in the
majority of Zygospyrida is apparent on the first view, and that it is
always demonstrated by an accurate examination of the sagittal ring and its
relation to the longitudinal constriction of the cephalis (compare p.
1019). The basal plate or cortinar plate exhibits usually four typical
pores (two smaller jugular, _i_, and two larger cardinal, _k_), but this is
by no means a general rule, as Bütschli thought; moreover, instead of four
cortinar pores, there are frequently found three or six or some other
numbers (compare above, p. 1018).

The top of the cephalis in the majority of Zygospyrida bears an apical
horn, as an upper prolongation of the dorsal rod of the sagittal ring; it
is often of unusual size and shape (Pl. 85, figs. 5-11; Pl. 95, fig. 8,
&c.). In several genera two lateral or frontal horns are developed on both
sides of the former (Pl. 84, figs. 9-12; Pl. 86, figs. 5-13). Sometimes
these two alone are present, while the original apical horn is lost by
reduction (Pl. 95, fig. 12). In other genera the apical face bears no
horns; probably they are lost by reduction.

The greatest variety of forms is produced in the Zygospyrida by the
different number, disposition, and shape of the feet, or the basal
apophyses arising from the base of the cephalis. Regarding these remarkable
differences, we may distinguish eight subfamilies. The common ancestral
group of all are probably the Tripospyrida, which possess the three typical
basal feet of _Cortina_ and _Cortiniscus_, an odd caudal and two paired
pectoral feet (Pl. 84). From these may be derived the Dipospyrida (Pl. 85)
by loss of the caudal foot, the Tetraspyrida by development of an odd
sternal foot (Pl. 53, figs. 7, 8, 19), and the Hexaspyrida by development
of three secondary interradial between the three primary perradial feet.
The Pentaspyrida may have been derived from the latter by loss of the
sternal foot (Pl. 95, figs. 9-11), and the Therospyrida by loss of the two
sagittal feet (Pl. 89, figs. 5, 6). The Polyspyrida bear numerous (seven to
twelve or more, often twenty to thirty) basal feet, forming a corona around
the cortinar plate (Pl. 87); they may have been derived from the
Tripospyrida or Hexaspyrida by further multiplication of the feet. Finally,
the Circospyrida exhibit no feet at all (Pl. 89, figs. 7-12); they may be
derived either from one of the preceding groups by complete reduction and
loss of the basal apophyses, or directly from those Semantida which have no
feet (_Semantis_, _Semantrum_, _Clathrocircus_, &c.).

{1024}_Synopsis of the Genera of Zygospyrida._

  -------------------------------------------------------------------------
  I. Subfamily Tripospyrida.
     Three basal feet. (One odd caudal and two paired pectoral.)
  -------------------------------------------------------------------------
  Apex of the shell with one horn,                   441. _Tripospyris_.

  Apex of the shell with three horns,                442. _Triceraspyris_.

  Apex of the shell without horns,                   443. _Tristylospyris_.

  Apex with two large coryphal holes, right and
   left,                                             444. _Cephalospyris_.
  -------------------------------------------------------------------------
  II. Subfamily Dipospyrida.
      Two basal lateral feet. (Originally the two pectoral feet.)
  -------------------------------------------------------------------------
  Two feet free, not    {Feet simple,   }One horn,   445. _Dipospyris_.
    grown together.     { not branched, }
                        { without       }
                        { lateral       }No horn,    446. _Brachiospyris_.
                        { spines.       }
                        {
                        {Feet branched  }One horn,   447. _Dendrospyris_.
                        { like a tree.  }
                        {
                        {Feet with a    }
                        { series of     }One horn,   448. _Dorcadospyris_.
                        { lateral       }
                        { spines.       }

  Two feet grown        {Feet simple,                449. _Gamospyris_.
   together and         {
   uniting to form a    {Feet with a series of
   ring. Apex with a    { lateral spines,            450. _Stephanospyris_.
   horn.
  -------------------------------------------------------------------------
  III. Subfamily Tetraspyrida. Two sagittal and two lateral feet.
  -------------------------------------------------------------------------
                             {Apex with one horn,    451. _Tetraspyris_.
  Feet simple, not branched. {
                             {Apex without a horn,   452. _Tessarospyris_.
  -------------------------------------------------------------------------
  IV. Subfamily Hexaspyrida. Six basal feet.
  -------------------------------------------------------------------------
  Two sagittal, two pectoral,{Apex with one horn,    453. _Hexaspyris_.
   and two tergal feet.      {
                             {Apex with three horns, 454. _Liriospyris_.
                             {
                             {Apex without a horn,   455. _Cantharospyris_.
  -------------------------------------------------------------------------
  V. Subfamily Pentaspyrida. Five basal feet.
  -------------------------------------------------------------------------
  One caudal, two pectoral,  {Apex with one horn,    456. _Clathrospyris_.
   and two tergal feet.      {
                             {Apex with three horns, 457. _Ægospyris_.
                             {
                             {Apex without a horn,   458. _Pentaspyris_.
  -------------------------------------------------------------------------
  VI. Subfamily Therospyrida.
      Four paired lateral feet. (Two pectoral and two tergal.)
  -------------------------------------------------------------------------
  Apex with one horn,                                459. _Zygospyris_.

  Apex with three horns (one apical and two
   frontal),                                         460. _Elaphospyris_.

  Apex with two lateral or frontal horns,            461. _Taurospyris_.

  Apex without a horn,                               462. _Therospyris_.

  VII. Subfamily Polyspyrida. Numerous (seven to twelve or more)
  basal feet.
  -----------
  Apex with one horn,                                463. _Petalospyris_.

  Apex with three horns (one apical and two
   frontal),                                         464. _Anthospyris_.

  Apex with numerous horns,                          465. _Ceratospyris_.

  Apex without a horn,                               466. _Gorgospyris_.

  VIII. Subfamily Circospyrida. No basal feet.
  --------------------------------------------
  Apex with one horn,                                467. _Circospyris_.

  Apex without a horn,                               468. _Dictyospyris_.



{1025}Subfamily 1. TRIPOSPYRIDA, Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# tripoda, with three descending basal feet (the
same as in _Cortina_, an odd posterior or caudal foot and two paired
anterior or pectoral feet).



Genus 441. _Tripospyris_,[59] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with three basal feet and one apical horn.

The genus _Tripospyris_ (Pl. 84, figs. 1-7) is in the large group of
#Spyroidea# probably the most original and typical form, from which, as a
common ancestral form, all other genera of this polymorphous suborder may
be derived. The shell is usually shaped like a nut or thorax, and exhibits
two paired lateral chambers, which are separated by a distinct sagittal
ring and a slighter or deeper sagittal constriction. The dorsal rod of the
ring is prolonged at the upper pole into an ascending apical horn, at the
lower pole into a descending caudal foot, whilst two paired pectoral or
lateral feet arise from the anterior pole of the basal rod. These three
divergent basal feet and the apical horn are the same four typical radial
spines which we have encountered already in _Plagoniscus_ (Plagonida), in
_Plectaniscus_ (Plectanida), in _Cortina_ (Stephanida), and in
_Cortiniscus_ (Semantida). Compare above, p. 891. From all these
#Plectellaria#, _Tripospyris_ differs in the development of a complete
bilocular lattice-shell, having the characters of the true #Spyroidea#. The
numerous species of this genus may be placed in different subgenera,
according to the different number of collar pores or cortinar pores in the
basal plate (two, three, four, six, or more). These differences are very
important, however difficult to make out; the following system therefore is
a provisional one, and requires further accurate observations.



Subgenus 1. _Tripospyrantha_, Haeckel.

_Definition._--Basal plate with two large pores only (the primary jugular
pores of _Semantis_).


1. _Tripospyris cortina_, n. sp. (Pl. 95, fig. 1).

Shell ovate, smooth, about as long as broad, with slight ovate sagittal
stricture, and broad primary ring in its wall. Basal plate with two large
kidney-shaped collar pores only (cardinal pores). Facial and occipital
plates each with two pairs of large annular pores, and ten to twelve pairs
of small lateral pores. Apical horn and the three basal feet of equal
length, one and a half times as long as the shell, three-sided prismatic,
straight, divergent.

_Dimensions._--Shell 0.08 long, 0.09 broad; horn and feet 0.15 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


{1026}2. _Tripospyris cortiniscus_, n. sp. (Pl. 84, fig. 6).

Shell ovate, smooth, one and a third times as long as broad, with sharp
ovate sagittal stricture and broad primary ring. Basal plate with two large
cardinal pores only. Occipital plate with two pairs of very large pores;
facial plate and lateral sides with numerous smaller irregular roundish
pores. Apical horn small, conical, curved, half as long as the three basal
feet, which are club-shaped and three-edged, with thinner bases and half as
long as the shell, strongly divergent.

_Dimensions._--Shell 0.12 long, 0.09 broad; horn 0.03 long, feet 0.06 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Tripospyris semantis_, n. sp. (Pl. 84, figs. 2, 3).

Shell subspherical, smooth, somewhat broader than long, with slight
sagittal stricture and subcircular parietal primary ring. Basal plate with
two large semicircular cardinal pores. Facial and occipital plate each with
two pairs of large annular pores and an odd large subapical pore; lateral
sides with very numerous small roundish pores. Apical horn and caudal foot
club-shaped, half as long as the shell, angular, simple; the two pectoral
feet somewhat longer, nearly vertical, and at the distal end with a small
incision, nearly forked.

_Dimensions._--Shell 0.1 long, 0.12 broad; horn and feet 0.05 to 0.07 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


4. _Tripospyris diomma_, n. sp. (Pl. 84, fig. 5).

Shell thorax-shaped, smooth, twice as broad as long, with deep sagittal
stricture, two vaulted ovate bosoms and smaller ovate internal primary
ring. Basal plate with two large ovate cardinal pores. Facial plate with
three pairs, occipital plate with four pairs of large annular pores; the
other lattice-work loose, with small and numerous irregular polygonal
pores. Apical horn and caudal feet slender and thin, curved, shorter than
half the shell; two pectoral feet also small, widely divergent, more or
less curved, deeply forked.

_Dimensions._--Shell 0.1 long, 0.16 broad; horn and feet 0.2 to 0.25 long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.



Subgenus 2. _Tripospyrella_, Haeckel.

_Definition._--Basal plate with three large collar pores (two paired
posterior cardinal pores, and an odd anterior sternal pore).


5. _Tripospyris triomma_, Haeckel.

  _Ceratospyris triomma_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xxi. fig. 3.

Shell subspherical, tuberculate, with slight sagittal stricture and
circular internal ring. Basal plate with three large pores, which are
sometimes (but not in every specimen) surrounded by a {1027}circle of very
small pores. The other lattice-work with numerous small roundish pores.
Apical horn small, oblique, about as long as the shell. Three feet very
large, cylindrical, curved, widely divergent, four to five times as long as
the shell. (In Ehrenberg's description the caudal foot is erroneously
described as "frontal spine"; its figure exhibits the basal plate.)

_Dimensions._--Shell 0.07 to 0.09 diameter; horn 0.06 long, feet 0.3 to 0.4
long.

_Habitat._--Fossil in Tertiary rocks of Barbados.


6. _Tripospyris conifera_, n. sp. (Pl. 84, figs. 7, 7_a_).

Shell nearly hemispherical, papillate, with slight sagittal stricture and
semicircular internal ring. Basal plate with three large pores (sometimes,
as in the figured specimen, with some small accessory peripheral pores).
The other lattice-work with subregular circular pores. Apical horn shorter
than the three basal feet, but of similar form, like an elegant ovate
dimpled cone, spinulate, with a smooth spindle-shaped pedicle, about as
long as the shell.

_Dimensions._--Shell 0.08 long, 0.1 broad; horn 0.06 long, feet 0.08 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


7. _Tripospyris triplecta_, n. sp. (Pl. 95, fig. 2).

Shell thorax-shaped, spiny, with deep sagittal stricture and semicircular
internal ring. Basal plate with three large collar pores. Facial plate with
four pairs, occipital plate with three pairs of large annular pores; the
other pores small, subregular, circular. Apical horn and the feet slender,
three-sided pyramidal, about as long as the shell.

_Dimensions._--Shell 0.1 long, 0.11 broad; horn and feet 0.1 to 0.15 broad.

_Habitat._--Mediterranean, Corfu (Haeckel), surface.



Subgenus 3. _Tripospyrissa_, Haeckel.

_Definition._--Basal plate with two pairs of collar pores (two larger
posterior cardinal pores and two smaller anterior jugular pores).


8. _Tripospyris semantrum_, n. sp. (Pl. 95, fig. 3).

Shell thorax-shaped, thorny, with deep sagittal stricture and subcircular
ring. Basal plate with four large collar pores (two smaller ovate jugular,
and two larger pentagonal cardinal pores). Facial and occipital plates also
each with two pairs of large annular pores; lateral sides with smaller
irregular polygonal pores. Apical horn and the three feet slender,
prismatic, divergent, longer than the shell.

_Dimensions._--Shell 0.07 long, 0.08 broad; horn and feet 0.11 to 0.13
long.

_Habitat._--South Atlantic, Cape of Good Hope (Wilhelm Bleek), surface.


{1028}9. _Tripospyris capitata_, n. sp. (Pl. 84, fig. 1).

Shell subspherical, spiny, with slight sagittal stricture and ovate
internal ring. Basal plate with four large collar pores. Facial plate with
three pairs and occipital plate with two pairs of large roundish annular
pores; lateral lattice with smaller irregular pores. Apical horn and the
three feet subcylindrical, about half as long as the shell, straight,
divergent, with a spherical, spinulate knob at the distal end.

_Dimensions._--Shell 0.09 long, 0.1 broad; horn and feet 0.05 to 0.06 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


10. _Tripospyris clavata_, Haeckel.

  _Ceratospyris clavata_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. p. 539, Taf. xxxii. fig. 13, _a-c_.

Shell subspherical, compressed, rough, with slight sagittal stricture and
ovate internal primary ring. Basal plate with four large collar pores (fig.
13_a_, _loc. cit._). The other lattice-work with irregular small roundish
pores. Apical horn and the three feet short and thick, scarcely half as
long as the shell, with a roundish spinulate knob at the distal end.

_Dimensions._--Length of the shell 0.07 long, 0.08 broad; horn and feet
0.02 to 0.03 long.

_Habitat._--Fossil in Barbados.


11. _Tripospyris tessaromma_, n. sp.

Shell nearly cubical, spiny, with deep sagittal stricture and subcircular
ring. Basal plate with four large collar pores. Facial and occipital plates
each also with two pairs of large square annular pores; lateral pores
irregular polygonal. Apical horn half as long as the feet, which are three
times the length of the shell, cylindrical, slightly curved.

_Dimensions._--Shell 0.1 long, 0.12 broad; horn 0.15 long, feet 0.3 long.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.



Subgenus 4. _Tripospyromma_, Haeckel.

_Definition._--Basal plate with six or more collar pores. Commonly two
small anterior jugular pores, two large middle cardinal pores, and two
small posterior cervical pores; sometimes several small accessory collar
pores.


12. _Tripospyris hexomma_, n. sp. (Pl. 95, fig. 4).

Shell thorax-shaped, tuberculate, with deep sagittal stricture and
semicircular internal primary ring. Basal plate with three pairs of pores.
Facial plate with two pairs, occipital plate with four pairs of large
annular pores. Lateral pores smaller, irregular, polygonal. Apical horn and
caudal foot half as long as the shell and as the two pectoral feet; all
four spines cylindrical, two to three times as long as the shell, slightly
curved.

_Dimensions._--Shell 0.1 long, 0.12 broad; horn and feet 0.2 to 0.4 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


{1029}13. _Tripospyris semantidium_, n. sp.

Shell nut-shaped, thorny, with sharp sagittal stricture and subcircular
ring. Basal plate with three pairs of large pores. Facial and occipital
plates each with three pairs of large squarish pores. Lateral pores small
and numerous, irregular roundish. Apical horn half as long as the shell and
the three feet; all four spines straight, cylindrical, with thickened
club-shaped end.

_Dimensions._--Shell 0.12 long, 0.13 broad; horn 0.06 long, feet 0.15.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


14. _Tripospyris eucolpos_, n. sp. (Pl. 84, fig. 4).

Shell thorax-shaped, smooth, with two vaulted bosoms, separated by a deep
sagittal stricture and an internal primary ring. Basal plate constricted,
with three pairs of collar pores. The other lattice-work with subregular
circular pores. Apical horn and the three feet shorter than the shell,
straight, divergent; their inner half thinner, cylindrical, smooth, their
outer half an ovate dimpled cone.

_Dimensions._--Shell 0.1 long, 0.13 broad; horn and feet 0.06 long.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.


15. _Tripospyris tribrachiata_, Haeckel.

  _Cladospyris tribrachiata_, Ehrenberg, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. xxi. fig. 8.

Shell subspherical, smooth, with slight sagittal stricture and numerous,
very small circular pores. Basal plate with numerous small pores. Apical
horn and the three divergent feet very large and stout, straight,
three-sided prismatic, with dentate edges, two to three times as long as
the shell.

_Dimensions._--Shell diameter 0.05; horn and feet 0.1 to 0.15 long.

_Habitat._--Fossil in Barbados.


16. _Tripospyris furcata_, n. sp. (Pl. 83, fig. 11).

Shell nut-shaped, smooth, with deep sagittal stricture and broad ring.
Basal plate with three pairs of small pores. Facial and occipital plates
each with a pair of very large holes. Apical horn and caudal foot simple
conical, two pectoral feet forked or irregularly branched.

_Dimensions._--Shell 0.08 long, 0.12 broad; horn and feet 0.05 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 442. _Triceraspyris_,[60] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with three basal feet and three coryphal
horns.

The genus _Triceraspyris_ has arisen from the preceding ancestral
_Tripospyris_ by the development of two paired frontal horns, so that the
shell here bears six appendages, {1030}three superior or coryphal spines
and three inferior or basal spines; two of these are odd and dorsal (the
apical horn and the caudal foot), the four others are paired and ventral
(the frontal horns and the pectoral feet). The numerous species of this
genus may be divided into three subgenera, according to the simple or
branched shape of the ascending horns and of the descending feet.



Subgenus 1. _Triospyris_, Haeckel, 1881, Prodromus, p. 441.

_Definition._--Horns and feet simple, not branched nor forked.


1. _Triceraspyris tripodiscus_, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores
irregular roundish, two pairs of larger pores on each side of the ring.
Basal plate with three large pores. Horns and feet slender cylindrical,
straight, divergent; three horns about as long as the shell, three feet
twice as long.

_Dimensions._--Shell 0.06 long, 0.08 broad; horn 0.05 long, feet 0.1.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.


2. _Triceraspyris cortiniscus_, n. sp.

Shell subspherical, smooth, with slight sagittal stricture. Pores small and
numerous, subregular roundish. Basal plate with two large pores (?). Apical
horn conical, short, half as long as the shell and the two lateral horns,
which are curved outwards. All three feet equal, cylindrical, strongly
curved and divergent, twice to three times as long as the shell.

_Dimensions._--Shell 0.07 long, 0.08 broad; horn 0.04 to 0.08 long, feet
0.15 to 0.2 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


3. _Triceraspyris didiceros_, Haeckel.

  _Ceratospyris didiceros_, Ehrenberg, 1875, Abhandl. d. Akad. d. Wiss.
  Berlin, p. 66, Taf. xxi. fig. 6.

Shell nut-shaped, thorny, with superficial sagittal stricture. Pores large,
irregular roundish. Basal plate with four larger pores. Apical horn and
caudal foot small, conical, shorter than half the shell. The two frontal
horns longer, slender conical. The two pectoral feet very large,
cylindrical, nearly parallel, vertical, slightly curved, twice to three
times as long as the shell.

_Dimensions._--Shell 0.07 long, 0.09 broad; two sagittal spines 0.02 long,
two lateral horns 0.04 long, two lateral feet 0.15 to 0.25 long.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Triospyrium_, Haeckel.

_Definition._--Horns simple, not branched; feet forked or branched.


{1031}4. _Triceraspyris furcata_, Haeckel.

  _Ceratospyris furcata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 8.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores
numerous, irregular roundish. Basal plate with four large pores. Three
horns small, conical, shorter than half the shell. Three feet large,
cylindrical, curved, about twice as long as the shell, forked at the distal
end.

_Dimensions._--Shell 0.07 long, 0.08 broad; horns 0.02 long, feet 0.1 to
0.12 long.

_Habitat._--Fossil in Barbados.


5. _Triceraspyris giraffa_, n. sp. (Pl. 84, fig. 11).

Shell nut-shaped, mammillate, with slight sagittal stricture. Pores
numerous, subregular circular. Basal plate with nine pores (three larger
central and three alternate pairs of smaller peripheral, as in Pl. 87, fig.
2). Three horns equal, straight, divergent, shorter than the shell, in the
basal half cylindrical, in the distal half spindle-shaped. Three feet
cylindrical, twice as long as the shell, nearly parallel, vertical, at the
distal end divergent, with a recurved branch near the base.

_Dimensions._--Shell 0.08 long, 0.1 broad; horns 0.05 to 0.07 long, feet
0.16 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


6. _Triceraspyris gazella_, n. sp. (Pl. 84, fig. 9).

Shell nut-shaped, tuberculate, with sharp sagittal stricture. Pores large,
irregular roundish; two or three pairs of larger pores on each side of the
ring. Basal plate with three large triangular pores. Three horns simple,
about as long as the shell, the apical straight, the two frontal elegantly
curved. Three feet somewhat longer, slender, curved, with a recurved branch
near the base, repeatedly forked at the distal end.

_Dimensions._--Shell 0.06 long, 0.09 broad; horn 0.05 long, feet 0.08 long.

_Habitat._--Indian Ocean (Cocos Islands), surface (Rabbe).


7. _Triceraspyris corallorrhiza_, n. sp. (Pl. 84, fig. 12).

Shell nut-shaped, spiny, with deep sagittal stricture. Pores irregular
polygonal or roundish. Basal plate with two large semicircular pores. Three
horns slender, simple, about half as long as the shell. Three feet of the
same length, slender, divergent, irregularly branched like coral.

_Dimensions._--Shell 0.06 long, 0.09 broad; horn and feet 0.03 to 0.05
long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


8. _Triceraspyris maniculata_, n. sp.

Shell subspherical, smooth, without external sagittal stricture. Pores
subregular circular. Basal plate with four large pores (?). Three horns
simple, straight, divergent, spindle-shaped, half {1032}as long as the
shell. Caudal foot of the same form, twice as long. Two pectoral feet
cylindrical, curved, twice as long as the shell, palmate, divided at the
distal end into five short fingers.

_Dimensions._--Shell 0.08 diameter; horns 0.04 long; lateral feet 0.12
long.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


9. _Triceraspyris longicornis_, n. sp.

Shell nut-shaped, papillate, with deep sagittal stricture. Pores irregular
roundish. Basal plate with six pores (?). Apical horn short, conical, two
frontal horns very large, curved, widely divergent, longer than the shell.
Three feet of about the same length, irregularly branched.

_Dimensions._--Shell 0.08 long, 0.12 broad; lateral horns and feet 0.15 to
0.2 long.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.



Subgenus 3. _Triospyridium_, Haeckel.

_Definition._--Horns and feet forked or branched.


10. _Triceraspyris damaecornis_, n. sp.

Shell nut-shaped, smooth, compressed, with broad sagittal ring. Pores
irregular roundish; one pair of very large pores on each side of the ring.
Basal plate with four large collar pores. Three horns and three feet short,
divergent, slightly curved, about half as long as the shell, irregularly
branched. (In general form very similar to _Elaphospyris damaecornis_, Pl.
84, fig. 10, with which I formerly confounded it.)

_Dimensions._--Shell 0.08 long, 0.12 broad; horns and feet 0.04 long.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


11. _Triceraspyris arborescens_, n. sp.

Shell subspherical, with deep sagittal stricture. Pores irregular roundish;
three pairs of larger pores on both sides of the ring. Basal plate with two
large collar pores. Three horns about half as long as the shell, with few
irregular terminal branches. (Beginning of a cupola.) Three feet strong,
cylindrical, twice as long as the shell, richly branched, arborescent.

_Dimensions._--Shell 0.09 long, 0.1 broad; horns 0.05 long, feet 0.2 long.

_Habitat._--Indian Ocean (Madagascar), Rabbe, surface.



Genus 443. _Tristylospyris_,[61] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with three basal feet, without apical horn.

The genus _Tristylospyris_ exhibits in general the same structure as the
typical genus _Tripospyris_, its ancestral form. It differs from the latter
in the absence of the apical {1033}horn, which is completely reduced, and
may therefore be regarded as the simplest prototype of all tripodal
Cyrtellaria without a horn.



Subgenus 1. _Tristylospyrula_, Haeckel.

_Definition._--Feet simple, not branched nor forked.


1. _Tristylospyris palmipes_, n. sp. (Pl. 84, fig. 14).

Shell companulate, smooth, with slight sagittal stricture. Pores irregular
roundish, three pairs of larger annular pores on each side of the broad
ring. Basal plate with four large collar pores. Feet half as long as the
shell, slightly divergent, straight, prismatic, with a broad, hand-like,
radially striped plate at the distal end.

_Dimensions._--Shell 0.1 long, 0.09 broad; feet 0.06 long.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.


2. _Tristylospyris scaphipes_, n. sp. (Pl. 84, fig. 13).

Shell nut-shaped, smooth, with sharp sagittal stricture. Pores very small
and numerous, circular; two pairs of larger pores on both sides of the
ring. Basal plate with four large pores (?). Feet about half as long as the
shell, angular, shovel-shaped, straight, parallel, vertical.

_Dimensions._--Shell 0.06 long, 0.08 broad; feet 0.04 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


3. _Tristylospyris clavipes_, n. sp. (Pl. 84, fig. 15).

Shell nut-shaped, rough, with deep sagittal stricture. Pores small,
subregular circular. Basal plate with three large pores. Feet about as long
as the shell, slender, straight, divergent, with a spinulate knob at the
thickened distal end.

_Dimensions._--Shell 0.06 long, 0.08 broad; feet 0.05 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


4. _Tristylospyris triceros_, Haeckel.

  _Ceratospyris triceros_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xxi. fig. 5.

Shell nut-shaped, tuberculate, without external sagittal stricture. Pores
circular, not numerous. Basal plate with four large collar pores. Feet
large, cylindrical, three to four times as long as the shell, strongly
curved and divergent.

_Dimensions._--Shell 0.05 long, 0.07 broad; feet 0.15 to 0.2 long.

_Habitat._--Fossil in Barbados.



{1034}Subgenus 2. _Tristylospyrium_, Haeckel.

_Definition._--Feet forked or branched.


5. _Tristylospyris furcata_, n. sp.

Shell subspherical, rough, with slight sagittal stricture. Pores subregular
circular. Basal plate with three large collar pores. Feet cylindrical,
three to four times as long as the shell, strongly curved and divergent, at
the distal end forked, with two short (sometimes ramified) branches.

_Dimensions._--Cephalis 0.08 long, 0.09 broad; feet 0.2 to 0.3 long.

_Habitat._--South Atlantic (off Patagonia), Station 318, surface.


6. _Tristylospyris ramosa_, n. sp. (Pl. 52, fig. 23).

Shell subspherical, tuberculate, with a prominent sagittal ring. Pores
irregular roundish. Basal plate with three large pores. Feet large,
straight, widely divergent, about twice as long as the shell, prismatic,
irregularly branched. (Compare the following species.)

_Dimensions._--Shell 0.08 in diameter; feet 0.15 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


7. _Tristylospyris tripodiscium_, n. sp. (Pl. 52, fig. 22).

Shell subovate, tuberculate, very similar to the preceding species. It
differs from this in the very different size of the irregular pores and the
greater breadth of the pedal branches. The basal plate in a complete
specimen (observed afterwards from the base) exhibited four large collar
pores of the usual form, whilst in the similar preceding species it had
three pores. In the similar _Tripodiscium sphærocephalum_ (Pl. 52, fig. 21)
the basal mouth is quite simple and open.

_Dimensions._--Shell 0.09 long, 0.1 broad; feet 0.12 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Genus 444. _Cephalospyris_,[62] Haeckel, 1881, Prodromus, p. 441 (_sensu
emend._).

_Definition._--#Zygospyrida# with three basal feet and two large apical
openings or coryphal holes, one on each side of the ring-apex. No true
horns.

The genus _Cephalospyris_ comprises some few Tripospyrida of very peculiar
shape, differing from all other Zygospyrida in the possession of two large
apical holes or coryphal apertures, lying on each side of a latticed
sagittal septum, which is formed by the upper part of the sagittal ring.
The sagittal stricture is deep, with a complete {1035}primary ring. The
vertical axis of the slender ovate shell is much greater than the
transverse. The network is very delicate, with very small and numerous
triangular or polygonal pores. The central capsule encloses peculiar
concrements (Pl. 96, fig. 28).


1. _Cephalospyris cancellata_, n. sp. (Pl. 83, fig. 10).

Shell slender ovate, two and a half times as long as broad, with deep
sagittal stricture and complete ring. Network very delicate, with very
small and numerous, irregular polygonal pores. The two large apical holes
are separated by a latticed triangular sagittal septum, the apex of which
represents a rudimentary horn. Basal plate with two large collar holes.
Three feet slightly curved, divergent, about half as long as the breadth of
the shell; the caudal foot slender, much thinner than the two stout
pyramidal pectoral feet.

_Dimensions._--Shell 0.32 long, 0.13 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Cephalospyris ovata_, n. sp.

Shell slender, ovate, twice as long as broad, with deep sagittal stricture
and complete ring. Network very delicate, with very small and numerous
triangular pores (on both poles intermingled with irregular polygonal
pores). The two large apical holes are separated by a latticed triangular
sagittal septum, the upper edge of which is concave and bears two
rudimentary horns. Basal plate with four large collar holes. Three feet
latticed, slightly curved, convergent, scarcely one-eighth as long as the
breadth of the shell. The central capsule filled up by concrements.

_Dimensions._--Shell 0.32 long, 0.16 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Cephalospyris triangulata_, n. sp. (Pl. 96, fig. 28).

Shell ovate, one and a half times as long as broad, with deep sagittal
stricture and complete ring. Network very delicate and regular, with small
triangular pores of equal size. The two large apical holes are separated by
a latticed semilunar septum, the upper edge of which is concave, and bears
two rudimentary horns. Basal plate with three large collar holes (?). Three
feet latticed, conical, nearly parallel and vertical (the caudal curved),
about half as long as the breadth of the shell. The ovate central capsule
contains peculiar amyloidal concentric concrements.

_Dimensions._--Shell 0.2 long, 0.14 broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



Subfamily 2. DIPOSPYRIDA, Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# dipoda, with two descending lateral basal feet
(probably corresponding to the pectoral feet of _Cortina_).



{1036}Genus 445. _Dipospyris_,[63] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with two simple free basal feet and one apical
horn.

The genus _Dipospyris_ and the following five genera represent together the
interesting subfamily of Dipospyrida, which always bear two opposite
lateral feet only. Therefore in this bipedal group the biradial or
bilateral type of the #Spyroidea# is particularly expressed. Such bipedal
forms never occur in the #Cyrtoidea#. The topographical relation of the two
lateral feet to the rods of the collar-plate, and to the cortinar pores
separated by these, leaves no doubt that they correspond to the pectoral
feet of _Cortina_ and _Tripospyris_, and therefore that the Dipospyrida
have originated from the Tripospyrida by loss of the caudal foot.
_Dipospyris_ is the simplest form of the Dipospyrida, with two simple free
feet.


1. _Dipospyris bipes_, n. sp.

Shell thorax-shaped, smooth, with deep sagittal stricture, two vaulted
bosoms, and subregular circular pores. Basal plate with two large collar
pores only. Horn and feet equal, conical, straight, about as long as the
shell; the feet widely divergent.

_Dimensions._--Shell 0.08 long, 0.12 broad; horn and feet 0.1 to 0.15 long.

_Habitat._--Fossil in Barbados.


2. _Dipospyris mystax_, Haeckel.

  _Ceratospyris mystax_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 6.

Shell elliptical spinulate, with slight collar stricture and large
subregular circular pores. Basal plate with three pores (?) Horn small
conical, oblique, shorter than the shell. Feet slender conical, longer than
the shell, slightly curved, divergent. At the base of the columella,
between the two feet, a small rudiment of the last caudal foot is visible.

_Dimensions._--Shell 0.06 long, 0.1 broad; horn 0.02, feet 0.12 long.

_Habitat._--Fossil in Barbados.


3. _Dipospyris cubus_, n. sp. (Pl. 83, fig. 18).

Shell box-shaped, subcubical, papillate, without external sagittal
stricture, with numerous subregular circular pores. Basal plate with three
very large collar pores, surrounded by a circle of smaller pores. Apical
horn short and thick, scarcely half as long as the shell. Feet of the same
form, longer than the shell, widely divergent.

_Dimensions._--Shell 0.08 long, 0.11 broad; horn 0.03 long, feet 0.14 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


{1037}4. _Dipospyris chelifer_, n. sp. (Pl. 85, fig. 3).

Shell elliptical, compressed, nodose, with deep sagittal stricture and
irregular roundish pores. Basal plate with three pores (?). Apical horn
stout, conical, twice to four times as long as the shell (often much longer
than in the figured specimen). Feet scarcely longer then the shell,
cylindrical, slightly curved towards one another.

_Dimensions._--Shell 0.08 long, 0.12 broad; horn 0.2 to 0.3 long, feet 0.1
to 0.15 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


5. _Dipospyris irregularis_, n. sp. Pl. 85, fig. 2.

Shell subspherical, without external sagittal stricture, with small
circular pores. Basal plate with four pores. Apical horn small, conical,
shorter than the shell. Feet three to four times as long as the shell,
cylindrical, irregularly curved, very variable in size and form.

_Dimensions._--Shell 0.08 long, 0.1 broad; horn 0.02 to 0.04 long, feet 0.2
to 0.3 long.

_Habitat._--Central Pacific, Stations 266 to 268, depth 2700 to 2900
fathoms.


6. _Dipospyris sigmopodium_, n. sp.

Shell violin-shaped, thorny, with deep sagittal stricture and irregular
roundish pores. Basal plate with four collar pores. Horn straight, conical,
about as long as the shell. Feet twice as long, cylindrical, markedly
divergent, S-shaped, curved.

_Dimensions._--Shell 0.08 long, 0.12 broad; horn 0.06 long, feet 0.2 long.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms; also fossil
in Barbados.


7. _Dipospyris forcipata_, n. sp. (Pl. 85, fig. 1).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate
with four larger and a circle of six to ten smaller pores. Horn
cylindrical, straight, two to three times as long as the shell. Feet three
to five times as long as the shell, cylindrical, semicircular, with
convergent and crossed distal ends. (If these ends grow together,
_Gamospyris_ arises.)

_Dimensions._--Shell 0.08 long, 0.11 broad; horn 0.15 to 0.2 long, feet 0.2
to 0.4 long.

_Habitat._--Central Pacific, Stations 263 to 268, depth 2600 to 3000
fathoms.



Genus 446. _Brachiospyris_,[64] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with two simple free basal feet, without
apical horn.

The genus _Brachiospyris_ differs from the preceding _Dipospyris_, its
ancestral form, only in the absence of the reduced apical horn, and
therefore bears to it a similar {1038}relation to that which the hornless
_Tristylospyris_, among the Tripospyrida, bears to the horned
_Tripospyris_. _Brachiospyris_ may therefore also be derived from
_Tristylospyris_ by loss of the caudal foot.


1. _Brachiospyris ocellata_, Haeckel.

  _Ceratospyris ocellata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 5.

Shell nut-shaped, thorny, with slight sagittal stricture and irregular
roundish pores. Basal plate with four large and four alternate pairs of
smaller pores. Two feet cylindrical, straight, divergent, two to three
times as long as the shell.

_Dimensions._--Shell 0.08 long, 0.11 broad; feet 0.2 to 0.3 long.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms; also fossil in
Barbados.


2. _Brachiospyris diacantha_, n. sp. (Pl. 95, fig. 5).

  ? _Ceratospyris diacantha_, Ehrenberg, 1872, Monatsber. d. k. preuss.
  Akad. d. Wiss. Berlin, p. 303.

Shell nut-shaped, tuberculate, compressed in the sagittal axis, convex on
the frontal face, concave on the sagittal face, with a slight sagittal
stricture; with large irregular roundish pores. Basal plate with three very
large pores. Two feet cylindrical, curved, S-shaped, about twice as long as
the shell.

_Dimensions._--Shell 0.06 long, 0.09 broad; feet 0.1 to 0.15 long.

_Habitat._--Western Tropical Pacific (Philippine Sea), Station 206, depth
2100 fathoms.



Genus 447. _Dendrospyris_,[65] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with two free lateral feet, forked or branched
like a tree. Apex with a horn.

The genus _Dendrospyris_ differs from its ancestral form _Dipospyris_ in
the ramification of the two large lateral feet, which descend from the base
of the shell, and are usually very large and stout, sometimes simply
forked.


1. _Dendrospyris stylophora_, Haeckel.

  _Ceratospyris stylophora_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 10.

Shell nut-shaped, thorny, with subregular circular pores. Basal plate with
four pores. Apical horn and the two divergent feet straight, cylindrical,
larger than the shell, forked at the distal end. {1039}(The size and number
of the fork-branches is variable; the horn is sometimes simple. In some
specimens a rudimentary remnant of the lost caudal foot is visible.)

_Dimensions._--Shell 0.08 long, 0.09 broad; horn and feet 0.1 to 0.12 long.

_Habitat._--Fossil in Barbados.


2. _Dendrospyris dirrhiza_, Haeckel.

  _Ceratospyris dirrhiza_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 9.

Shell nut-shaped, spiny, very similar to the preceding species. It differs
from that mainly in the growth of the cylindrical feet, which are not
straight and divergent, but more or less curved and convergent; their
distal ends are sometimes simply forked, sometimes repeatedly dichotomous.
The size and form of the apical horn are also very variable.

_Dimensions._--Shell 0.06 long, 0.08 broad; horn and feet 0.07 to 0.09
long.

_Habitat._--Fossil in Barbados.


3. _Dendrospyris bibrachiata_, Haeckel.

  _Cladospyris bibrachiata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. xxi. fig. 7.

Shell nut-shaped, smooth, with sharp stricture and numerous very small
circular pores. Apical horn and the two feet very large and stout,
straight, prismatic, with irregular lateral branches on their edges, twice
to four times as long as the shell (The horn in the Ehrenberg's figure is
broken off.) This species is closely allied to _Tripospyris tribrachiata_.

_Dimensions._--Shell 0.05 long, 0.06 broad; horn and feet 0.1 to 0.2 long.

_Habitat._--Fossil in Barbados.


4. _Dendrospyris furcata_, n. sp.

Shell subspherical, tuberculate, with irregularly roundish pores. Basal
plate with two large pores. Apical horn simple, conical, as long as the
shell. Feet cylindrical, twice as long, in the proximal half parallel,
vertical, in the distal half with two stout divergent equal fork-branches,
one of which is directed dorsally, the other ventrally.

_Dimensions._--Shell 0.07 long, 0.08 broad; horn 0.06 long, feet 0.1 to
0.15 long.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.


5. _Dendrospyris polyrrhiza_, n. sp. (Pl. 85, fig. 8).

Shell subspherical, rough, with subregular circular pores. Basal plate with
three pores (?). Apical horn simple, conical, half as long as the shell.
Feet cylindrical twice to three times as long as the shell, semicircular,
with a strong conical tooth in the middle of their outer convex edge; their
distal ends convergent, divided into a bunch of numerous short irregular
branches.

_Dimensions._--Shell 0.7 long, 0.08 broad; horn 0.03 long, feet 0.15 to
0.25 long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


{1040}6. _Dendrospyris ramosa_, n. sp.

Shell nut-shaped, spiny, with irregular roundish pores. Basal plate with
three pairs of pores. Apical horn cylindrical, spinulate, twice to three
times as long as the shell. Feet as long as the horn, S-shaped, widely
divergent, irregularly branched, with widely distant pointed branches.

_Dimensions._--Shell 0.08 long, 0.12 broad; horn and feet 0.2 to 0.3 long.

_Habitat._--North Atlantic, Station 353, depth 2965 fathoms.


7. _Dendrospyris arborescens_, n. sp. (Pl. 85, fig. 9).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate
with four central larger and ten to twelve peripheral smaller pores. Apical
horn cylindrical, twice as long as the shell, in the distal half spinulate
or tuberculate. Feet about three times as long as the shell, cylindrical,
nearly vertical, in the distal half irregularly branched, with dense
bunches of aggregated blunt branches.

_Dimensions._--Shell 0.07 long, 0.09 broad; horn and feet 0.12 to 0.18
long.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.



Genus 448. _Dorcadospyris_,[66] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with two free lateral feet armed with a series
of secondary spines. Apex with a horn.

The genus _Dorcadospyris_ and the closely allied _Stephanospyris_ differ
from the other Dipospyrida in the development of a series of secondary
spines on the convex outer margin of the two large curved lateral feet,
which therefore appear semipinnate. In some species this peculiar armature
attains an extraordinary size, whilst the shell itself is very small, as in
_Dorcadospyris dinoceras_ (Pl. 85, fig. 4).


1. _Dorcadospyris dentata_, n. sp. (Pl. 85, fig. 6).

Shell subspherical, tuberculate with small regular circular pores. Basal
plate with four larger pores. Apical horn three to four times as long as
the shell, slender conical, smooth. Feet more or less convexly curved
towards one another; the distal ends not crossed. In the convex edge of
each arm a series of five to ten smooth conical teeth, not longer than the
shell. This common species is very variable and often asymmetrical; the
figured specimen is an asymmetrical one, in which the two arms exhibit
different curves; in the normal form both arms have the same curve, now
more, now less convex.

_Dimensions._--Shell 0.06 long, 0.08 broad; horn 0.2, feet 0.03 long.

_Habitat._--Central Pacific, Stations 267 to 274, depth 2350 to 2925
fathoms.


{1041}2. _Dorcadospyris antilope_, n. sp. (Pl. 85, fig. 5).

Shell subspherical, tuberculate, with small regular circular pores. Basal
plate with four larger pores. Apical horn four to six times as long as the
shell, straight, cylindrical, smooth. Feet of the same length, crescentic
or nearly semicircular, with crossed distal ends. On the convex edge of
each foot a series of twelve to fifteen smooth conical teeth, partly longer
than the shell. (Very variable in size and curvature of the feet, and
number of their teeth.)

_Dimensions._--Shell 0.09 long, 0.11 broad; horn and feet 0.4 to 0.6 long.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.


3. _Dorcadospyris lunulata_, n. sp.

Shell subspherical spinulate, nearly of the same shape as in the preceding
species, but with a short conical horn (scarcely as long as the shell); the
feet are much mere slender, crescentic, and bear twenty to thirty smaller
smooth conical teeth (shorter than the shell). The distal ends of the feet
are crossed.

_Dimensions._--Shell 0.08 long, 0.09 broad; horn 0.06 long, feet 0.03 to
0.06 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


4. _Dorcadospyris decussata_, n. sp. (Pl. 85, fig. 7).

Shell subspherical, smooth, very similar to that of the two preceding
species. Horn small conical, about as long as the shell. Feet more than
semicircular, more strongly curved than in any other species, each with
four to eight small conical teeth, shorter than the shell; distal ends
crossed. (In this species also, besides the normal symmetrical form, there
often occurs an asymmetrical form of the two feet; one of these frequent
anomalies is shown in fig. 7.)

_Dimensions._--Shell 0.06 long, 0.08 broad; horn 0.05, feet 0.2 to 0.5
long.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


5. _Dorcadospyris dinoceras_, n. sp. (Pl. 85, fig. 4).

Shell subspherical, tuberculate, with subregular circular pores. Basal
plate with four larger central and eight to twelve smaller peripheral
pores. Horn about as long as the shell, in the basal half prismatic,
smooth, in the distal half ovate or strobiliform, spiny. Feet very large
and strongly curved, together nearly heart-shaped, four to six times as
long as the shell. Each foot bears on its outer convex side a series of
fifteen to twenty or more strong conical teeth, which are again spinulate,
perpendicular to the foot, and longer than the shell.

_Dimensions._--Shell 0.08 long, 0.09 broad; horn 0.07 long, feet 0.3 to 0.5
long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



{1042}Genus 449. _Gamospyris_,[67] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with two simple lateral feet, forming a ring
by union.

The genus _Gamospyris_ and the similar _Stephanospyris_ differ from all
other #Spyroidea# in the possession of a large basal ring, placed in the
frontal plane of the shell. This ring has been produced by concrescence of
the distal ends of the two large curved lateral feet of _Dipospyris_.


1. _Gamospyris circulus_, n. sp. (Pl. 83, fig. 19).

Shell subspherical, tuberculate, with subregular circular pores. Basal
plate with four larger collar pores. Apical horn pyramidal, about as long
as the shell. The connected feet form together a circular or nearly
circular smooth ring, the diameter of which is three to four times as great
as that of the shell.

_Dimensions._--Shell 0.08 long, 0.09 broad; diameter of the arm-ring 0.25
to 0.33.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


2. _Gamospyris annulus_, n. sp.

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate
with four large central and a circle of eight to twelve small peripheral
pores. Apical horn conical, twice as long as the shell. The connected arms
form together an elliptical smooth ring, which is five times as long and
three times as broad as the shell.

_Dimensions._--Shell 0.07 long, 0.09 broad; ring 0.33 long, 0.26 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Genus 450. _Stephanospyris_,[68] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Zygospyrida# with two lateral feet bearing a series of
secondary spines and forming a ring by union.

The genus _Stephanospyris_ exhibits the same peculiar armature of the
semipinnate lateral feet as its ancestral genus _Dorcadospyris_, but
differs from it in the concrescence of the distal ends of the feet, to form
a complete foot-ring. The former therefore bears to the latter the same
relation that _Gamospyris_ does to _Dipospyris_.


1. _Stephanospyris cordata_, n. sp. (Pl. 85, fig. 10).

Shell subspherical, tuberculate, with small regular circular pores. Basal
plate with four larger pores. Apical horn cylindrical, three times as long
as the shell, with three to four verticils {1043}of teeth. The connected
feet form a heart-shaped ring, four times as long and three times as broad
as the shell. Each foot bears on the outer convex edge four to six stout
conical teeth, shorter than the shell. Distal ends crossed and prominent.

_Dimensions._--Shell diameter 0.1; length of the arm-ring 0.4, breadth 0.3.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


2. _Stephanospyris verticillata_, n. sp. (Pl. 85, fig. 11).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate
with numerous small pores. Apical horn cylindrical, four to six times as
long as the shell, with six to ten verticils of teeth. The connected feet
form a circular ring, the diameter of which is four times as great as that
of the shell. Each foot bears ten to twelve conical teeth, about as long as
the shell. Distal ends not crossed and not prominent.

_Dimensions._--Diameter of the shell 0.1, of the arm-ring 0.4.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Stephanospyris excellens_, n. sp. (Pl. 83, fig. 20).

Shell subspherical, tuberculate, with regular circular pores. Basal plate
with numerous small pores. Apical horn cylindrical, twice as long as the
shell, with eight verticils of teeth. The connected feet form an ovate
ring, which is three times as long and two and a half times as broad as the
shell. Each foot bears eight conical spinulate teeth, about as long as the
shell. The crossed and prominent distal ends bear two parallel vertical
teeth.

_Dimensions._--Diameter of the shell 0.1, of the arm-ring 0.2 to 0.3.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Subfamily 3. TETRASPYRIDA, Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# tetrapoda, with four descending basal feet,
two of which are opposite in the sagittal plane (an odd caudal and an odd
sternal foot), whilst the two others are paired lateral or pectoral feet.



Genus 451. _Tetraspyris_,[69] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with four basal feet crossed in pairs (two
sagittal and two lateral). Apex with a horn.

The genus _Tetraspyris_ and the following closely allied _Tessarospyris_
represent together the small subfamily of Tetraspyrida, characterised by
the possession of four descending basal feet, three of which correspond to
the three original feet of the {1044}ancestral genera _Cortina_ and
_Tripospyris_, whilst the fourth in an odd anterior or sternal foot,
produced by anterior prolongation of the basilar segment of the sagittal
ring. Here, therefore, two opposed feet lie in the sagittal plane (a caudal
and a sternal foot), whilst the two others are the paired lateral or
pectoral feet, as also in _Stephanium_ and _Stephaniscus_, p. 965. The
Tetraspyrida ought not to be confounded with the Therospyrida (sixth
subfamily), in which the four feet have another signification.



Subgenus 1. _Tetrarrhabda_, Haeckel, 1881, p. 429.

_Definition._--Feet simple, not branched nor forked.


1. _Tetraspyris stephanium_, n. sp. (Pl. 95, fig. 6).

Shell nut-shaped, tuberculate, with deep sagittal stricture and small
roundish pores; three pairs of larger pores on each side of the ring. Basal
plate with four large collar pores. Apical horn stout conical, half as long
as the shell. Two pectoral feet somewhat longer than the two sagittal feet,
one and a half times as long as the shell. All four feet straight,
three-sided prismatic, strongly divergent.

_Dimensions._--Shell 0.08 long, 0.12 broad; horn 0.04 long, feet 0.08 to
0.12 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Tetraspyris cubica_, n. sp.

Shell nearly cubical, smooth, with slight sagittal stricture and small
polygonal pores; some larger pores on both sides of the ring. Basal plate
with four large collar pores. Apical horn and the four feet of equal size
and form, about as long as the shell, cylindrical in the basal, spindle
shaped in the distal half.

_Dimensions._--Shell 0.09 diameter; horn and feet 0.1 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; also fossil
in Barbados.



Subgenus 2. _Tetracorethra_, Haeckel, 1831, Prodromus, p. 429.

_Definition._--Feet branched or forked.


3. _Tetraspyris tetracorethra_, n. sp. (Pl. 53, figs. 19, 20).

  _Tetracorethra mirabilis_, Haeckel, 1881, Prodromus, p. 439, and Atlas,
  loc. cit.

Shell campanulate, tuberculate, with deep sagittal stricture and irregular
polygonal pores; two pairs of larger pores at the flattened occipital face
(fig. 20). Basal plate with four large collar pores. Apical horn very long,
thirty to forty times as long as the shell, slender three-sided prismatic,
straight, at the distal end irregularly branched, besom-shaped. Four basal
feet half as {1045}thick as the horn, eight to twelve times as long as the
shell, bristle-shaped, irregularly curved and branched, divergent, at the
distal end besom-shaped. Central capsule very large; the enclosed small
campanulate part sends out through the four collar pores four very long
club-shaped basal lobes, half as long as the feet; each lobe contains a
large oil-globule (fig. 19).

_Dimensions._--Shell 0.036 diameter; horn 1 to 1.5 mm. long, feet 0.3 to
0.4 long.

_Habitat._--Central Pacific, Station 270, surface.


4. _Tetraspyris calcarata_, n. sp.

Shell campanulate, smooth, very similar to that of the preceding species,
but differing in the following characters:--the two inferior occipital
pores are four times (in the preceding twice) as large as the two superior;
the apical horn bears at its distal end only three simple branches; the
sternal foot is smaller than the three others, arises higher, is more
divergent and curved, and bears at its base a large horizontal conical
spur.

_Dimensions._--Shell 0.035 diameter; horn 1 to 1.2 long, feet 0.2 to 0.3
long.

_Habitat._--Central Pacific, Station 266, surface.


5. _Tetraspyris scoparia_, n. sp.

Shell campanulate, rough, very similar to the two preceding species, but
differing in the following characters:--the four occipital pores are of
nearly equal size; the apical horn is simple, not branched; the four feet
are forked near the base, so that apparently eight feet diverge, each in
the distal half richly branched, besom-shaped.

_Dimensions._--Shell 0.038 diameter; horn 1 to 1.1 long, feet 0.4 to 0.5
long.

_Habitat._--Central Pacific, Station 268, surface.



Genus 452. _Tessarospyris_,[70] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with four basal feet crossed in pairs (two
sagittal and two lateral). Apex without horn.

The genus _Tessarospyris_ differs from the preceding _Tetraspyris_, its
ancestral genus, in the absence of the apical horn, and therefore bears to
it the same relation that _Tristylospyris_ does to _Tripospyris_.


1. _Tessarospyris clathrobursa_, n. sp. (Pl. 53, fig. 8).

  _Clathrobursa dictyopus_, Haeckel, 1881, Prodromus, p. 439, and Atlas,
  pl. liii. fig. 8.

Shell nearly ovate, strongly compressed, smooth, one and a half times as
long as broad, with deep sagittal stricture in the basal half. Pores very
small and numerous, irregularly roundish. Basal plate with four very large
triangular holes, two larger (posterior) cardinal, and two smaller
(anterior) {1046}jugular pores; above the latter (on the frontal face) two
large mental pores. Two pectoral feet large, half as long as the shell, at
the base fenestrated, vertical, and parallel. Two sagittal feet much
smaller, nearly horizontal, pyramidal (the caudal larger than the sternal
foot). Two longitudinal pectoral ribs arise on the frontal face.

_Dimensions._--Shell 0.21 long, 0.14 broad; lateral feet 0.1, sagittal feet
0.02.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


2. _Tessarospyris nuciformis_, n. sp.

Shell nut-shaped, papillate, with deep sagittal stricture. Pores irregular
roundish, on both sides of the ring three to six times as large as on the
lateral sides. Basal plate with four large pores. Two pectoral feet
cylindrical curved, twice as long as the shell and as the two sagittal
feet; the caudal is much stronger than the sternal foot.

_Dimensions._--Shell 0.06 long, 0.09 broad; lateral feet 0.1, sagittal feet
0.05 long.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


3. _Tessarospyris seminulum_, Haeckel.

  _Petalospyris seminulum_, Stöhr, 1880, Palæontogr., vol. xxvi. pl. iii.
  fig. 12.

Shell subspherical, smooth, with slight sagittal stricture and small
circular pores; some larger pores on both sides of the ring. Basal plate
with two large (lateral) pores only. Four feet nearly equal, short,
conical, divergent, scarcely one-fourth as long as the shell.

_Dimensions._--Shell 0.06 long, 0.08 broad; feet 0.016 long.

_Habitat._--Fossil in Tertiary rocks of Sicily (Grotte), Stöhr.



Subfamily 4. HEXASPYRIDA, Haeckel.

_Definition._--#Zygospyrida# hexapoda, with six descending basal feet;
three of these are primary (one odd caudal and two paired pectoral feet),
the other three are secondary, opposed diametrically to the former and
alternating with them (one odd sternal and two paired tergal feet).



Genus 453. _Hexaspyris_,[71] n. gen.

_Definition._--#Zygospyrida# with six basal feet and one apical horn.

The genus _Hexaspyris_ and the two following closely allied genera
represent together the peculiar subfamily of Hexaspyrida, and differ from
the other Zygospyrida in the possession of six descending basal feet; three
of these are the three original, perradial, or primary basal feet of
_Cortina_, _Cortiniscus_, _Plagoniscus_, _Plectaniscus_, _Tripospyris_,
&c.; the other three, usually opposed to the former diametrically, are
{1047}secondary or interradial; an odd sternal foot (opposed to the odd
caudal) and two paired tergal feet (opposed to the two paired pectoral).



Subgenus 1. _Hexaspyridium_, Haeckel.

_Definition._--Feet simple, not branched nor forked.


1. _Hexaspyris alterna_, n. sp.

Shell nut-shaped, smooth, with deep sagittal stricture and irregular
polygonal pores; on each side of the stricture two pairs of larger square
annular pores. Basal plate also with four larger collar pores. Apical horn
twice as long as the shell, conical. Three primary feet (the apical and the
two pectoral) slender, curved, as long as the horn; three secondary feet
(the sternal and the two tergal) are half as long as the former and more
highly inserted; all six feet strongly divergent, cylindrical, pointed.

_Dimensions._--Shell 0.06 long, 0.09 broad; horn 0.15 long, feet 0.08 to
0.14 long.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


2. _Hexaspyris setigera_, Haeckel.

  _Ceratospyris setigera_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 11.

  _Ceratospyris setigera_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. p. 539, Taf. xxxii. figs. 11_a_, 11_b_.

Shell nut-shaped, tuberculate, with a complete internal sagittal ring and
numerous small circular pores. Basal plate with four larger central and a
circle of twelve to twenty smaller peripheral pores. Apical horn half as
long as the shell, bristle-shaped. Three primary feet longer and more
deeply inserted than the three secondary feet; all six feet strongly
divergent, bristle-shaped, shorter than the shell.

_Dimensions._--Shell 0.06 long, 0.09 broad; horn 0.03 long; primary feet
0.05, secondary 0.02 long.

_Habitat._--Fossil in Barbados.


3. _Hexaspyris bütschlii_, Haeckel.

  _Ceratospyris triomma_, Bütschli (_non_ Ehrenberg), 1882, Zeitschr. f.
  wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. fig. 12, _a_, _b_.

Shell nut-shaped, spinulate, with a complete internal sagittal ring and
subregular circular pores. Basal plate with twelve pores (four larger
central and eight smaller peripheral). Apical horn stout, oblique, as long
as the shell. Six feet of equal length, slightly divergent, nearly
vertical, slender, three to four times as long as the shell.

_Dimensions._--Shell 0.05 long, 0.07 broad; horn 0.06, feet 0.15 to 0.2
long.

_Habitat._--Fossil in Barbados.


{1048}4. _Hexaspyris spinosa_, Haeckel.

  _Petalospyris spinosa_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 98, Taf.
  iii. fig. 14.

Shell subspherical, smooth, with slight sagittal stricture and irregular
polygonal pores; on each side of the stricture two pairs of larger pores.
Basal plate with two large pores only. Apical horn short, pyramidal, three
primary feet half as long as the shell and twice as long as the three
secondary feet. All six feet pyramidal, slightly divergent.

_Dimensions._--Shell 0.05 long, 0.07 broad; horn 0.02, feet 0.02 to 0.04
long.

_Habitat._--Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).


5. _Hexaspyris ophirensis_, Haeckel.

  _Petalospyris ophirensis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 297, Taf. ix. fig. 24.

Shell nut-shaped, with deep sagittal stricture and numerous irregular
roundish pores; two pairs of larger pores on each side of the stricture.
Apical horn short, curved. Six feet equal, divergent, straight, slender,
about as long as the shell.

_Dimensions._--Shell 0.05 long, 0.1 broad; horn 0.01, feet 0.05 to 0.08
long.

_Habitat._--Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.



Subgenus 2. _Hexacorethra_, Haeckel.

_Definition._--Feet forked or branched.


6. _Hexaspyris hexacorethra_, n. sp. (Pl. 95, fig. 8).

  _Hexacorethra magica_, Haeckel, 1882, Manuscript.

Shell campanulate, smooth, with sharp sagittal stricture and irregular
roundish pores. Basal plate with six larger collar pores. Apical horn very
long and thin, three-sided prismatic, straight, ten to twenty times as long
as the shell, branched at the distal end. Six feet thinner, bristle-shaped,
six to eight times as long as the shell, divergent, irregularly curved, in
the distal part branched, besom-shaped; the sternal foot at its base with a
large conical horizontal spur.

_Dimensions._--Shell 0.034 diameter; horn 0.4 to 0.8 long, feet 0.2 to 0.3
long.

_Habitat._--Central Pacific, Station 265, surface.


7. _Hexaspyris articulata_, Haeckel.

  _Ceratospyris articulata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 4.

Shell nut-shaped, tuberculate, with deep sagittal stricture and small
irregular roundish pores. Basal plate with six pores (?). Apical horn
conical, longer than the shell. Six feet very large, thick
{1049}cylindrical, divergent, three to four times as long as the shell,
with few irregular lateral branches (often much more developed than in
Ehrenberg's figure).

_Dimensions._--Shell 0.036 long, 0.05 broad; horn 0.05, feet 0.1 to 0.15
long.

_Habitat._--Fossil in Barbados.



Genus 454. _Liriospyris_,[72] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Zygospyrida# with six basal feet and three coryphal horns.

The genus _Liriospyris_ differs from the preceding _Hexaspyris_, its
ancestral form, in the possession of three coryphal horns (one odd apical
in the middle, and two paired frontal horns on each side of it); it
therefore bears to the latter the same relation that _Triceraspyris_ does
to _Tripospyris_.


1. _Liriospyris hexapoda_, n. sp. (Pl. 86, fig. 7).

Shell subspherical, smooth, with slight sagittal stricture and irregular
roundish pores; two to three pairs of large annular pores on each side of
the stricture. Basal plate with four large collar pores. Three horns and
six feet nearly of the same size and of similar form, conical, divergent,
about one-third as long as the shell.

_Dimensions._--Shell diameter 0.09 to 0.1; horns and feet 0.03 to 0.04
long.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


2. _Liriospyris clathrata_, Haeckel.

  _Dictyospyris clathrus_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig.
  25.

  _Dictyospyris clathrata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. xix. fig. 7.

  _Dictyospyris clathrata_, Bütschli, 1882, Zeitschr. f. Wiss. Zool., vol.
  xxxvi. pp. 506, 539; Taf. xxxii. figs. 10_a_, 10_b_.

  _Petalospyris clathrus_, Haeckel, 1862, Monogr. d. Radiol., p. 295.

Shell campanulate or nearly spherical, smooth, with slight sagittal
stricture. Three pairs of large annular pores on each side of the
stricture; a few smaller irregular pores on the lateral sides. Basal plate
with six large collar pores (Bütschli, _loc. cit._, fig. 10_a_). Three
horns and six feet nearly of the same size and form; short, conical,
slightly divergent or nearly parallel, shorter than half the ring. (The
size of the nine appendages is in this common species rather variable;
sometimes they are rudimentary, at other times much stronger than in the
good figure of Bütschli.)

_Dimensions._--Shell diameter 0.08 to 0.09, horns and feet 0.01 to 0.03.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific; also fossil in
Barbados and Sicily.


{1050}3. _Liriospyris heteropoda_, n. sp.

Shell nut-shaped, nodose, with deep sagittal stricture and small circular
pores; two pairs of larger pores on each side of the stricture. Basal plate
with four larger central and eight smaller peripheral pores. Apical horn
conical, as long as the shell and twice as long as the two curved frontal
horns. Three primary feet twice as long as the shell and as the three
secondary feet, which are more highly inserted. All six feet slender
curved, divergent.

_Dimensions._--Shell 0.07 long, 0.11 broad; horn and secondary feet 0.08
long, primary feet 0.15 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


4. _Liriospyris turrita_, Haeckel.

  _Ceratospyris turrita_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 1.

Shell ovate, campanulate, smooth, with sharp sagittal stricture and
irregular roundish pores; three to four pairs of larger pores on each side
of the stricture. Basal plate with four large collar pores. Three horns
short and stout, conical, fenestrated at the base. Six feet slender,
conical, nearly vertical, of equal size, only one-third as long as the
shell.

_Dimensions._--Shell 0.08 long, 0.06 broad; horns 0.01 long, feet 0.03
long.

_Habitat._--Fossil in Barbados.


5. _Liriospyris amphithecta_, n. sp. (Pl. 95, fig. 7).

Shell nut-shaped, tuberculate, with distinct sagittal stricture and
irregular roundish pores. Basal plate with six larger and twelve smaller
pores. Three horns conical, the apical as long as the shell and twice as
long as the curved frontal horns. Two pectoral feet cylindrical, very
large, curved, divergent, about three times as long as the shell and as the
four other feet, which are conical.

_Dimensions._--Shell 0.08 long, 0.12 broad; apical horn 0.08, frontal horns
0.05 long; length of the two pectoral feet 0.2, of the four others 0.06.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



Genus 455. _Cantharospyris_,[73] n. gen.

_Definition._--#Zygospyrida# with six basal feet, without apical horn.

The genus _Cantharospyris_ differs from the preceding two hexapodal genera
in the absence of horns on the coryphal face, and has therefore the same
relation to them that the hornless _Tristylospyris_ bears to the one-horned
_Tripospyris_ and the three-horned _Triceraspyris._


{1051}1. _Cantharospyris carabus_, n. sp.

Shell nut-shaped, with deep sagittal stricture and irregular roundish
pores. Basal plate with six larger pores. Six feet of different sizes,
cylindrical, curved; three primary feet (one caudal and two pectoral) about
as long as the shell and twice as long as the three secondary feet.

_Dimensions._--Shell 0.08 long, 0.12 broad; feet 0.05 to 0.09 long.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms; Central
Pacific, Station 268, depth 2900 fathoms.


2. _Cantharospyris ateuchus_, Haeckel.

  _Ceratospyris ateuchus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xxi. fig. 4.

Shell nut-shaped, tuberculate, with slight sagittal stricture and unequal
circular pores. Basal plate with six larger pores. The two pectoral feet
very large and stout, four to six times as long as the shell, widely
divergent, curved. The four other feet much smaller and thinner, about as
long as the shell.

_Dimensions._--Shell 0.06 long, 0.08 broad; length of the two larger feet
0.2 to 0.3, of the four smaller 0.05 to 0.07.

_Habitat._--Fossil in Barbados.


3. _Cantharospyris radicata_, Haeckel.

  _Ceratospyris radicata_, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad.
  d. Wiss. Berlin, p. 43; Mikrogeol., 1854, Taf. xxii. fig. 37.

  _Haliomma radicatum_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.
  Wiss. Berlin, p. 83.

  _Petalospyris radicata_, Haeckel, 1862, Monogr. d. Radiol., p. 295.

  _Petalospyris radicata_, Stöhr, 1880, Palæontogr., vol xxvi. p. 79, Taf.
  iii. fig. 11.

Shell nut-shaped, smooth, with slight sagittal stricture and irregular
roundish pores; two larger pores on each side of the ring. Basal plate with
six pores (?). Six feet of equal size and similar form, conical, divergent,
slightly curved, shorter than half the ring.

_Dimensions._--Shell 0.05 long, 0.08 broad; feet 0.02 long.

_Habitat._--Fossil in Barbados and Sicily.


4. _Cantharospyris platybursa_, n. sp. (Pl. 53, fig. 7).

  _Platybursa compressa_, Haeckel, 1881, Prodromus, p. 429; Atlas, pl. 53,
  fig. 7.

Shell smooth, nearly discoidal circular, markedly compressed in the
sagittal direction, with slight basal stricture. Pores very numerous,
irregular polygonal, with thin bars. Basal plate with four very large
pores. Six feet short, conical, nearly horizontally expanded. Two sagittal
feet (caudal {1052}and sternal) larger, about half as long as the shell
(shortened in the figure). The two sternal feet larger than the two small
or rudimentary tergal feet.

_Dimensions._--Shell 0.15 long, 0.13 broad; feet 0.02 to 0.06 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Subfamily 5. PENTASPYRIDA, Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# pentapoda, with five descending basal feet,
one odd caudal foot, and two pairs of lateral feet (two anterior or
pectoral, and two posterior or tergal feet).



Genus 456. _Clathrospyris_,[74] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with five basal feet and one apical horn.

The genus _Clathrospyris_ and the two following closely allied genera
represent together the small subfamily of Pentaspyrida, differing from the
other Zygospyrida in the possession of five descending feet on the basal
face. Three of these are the primary cortinar feet (of _Cortiniscus_,
_Plagoniscus_, _Tripospyris_, &c.), whilst the two others are secondary
tergal feet. The Pentaspyrida may therefore be probably derived from the
Hexaspyrida by loss of the odd anterior or sternal foot.


1. _Clathrospyris camelopardalis_, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores
irregular roundish. Basal plate with six pores (?). Two pectoral feet very
large, twice as long as the shell, cylindrical, curved. Two tergal feet
half as long and thick as the pectoral. Caudal foot and apical horn
straight, conical, half as long as the shell.

_Dimensions._--Shell 0.07 long, 0.09 broad; horn and odd caudal foot 0.04
long; pectoral feet 0.16, tergal 0.08 long.

_Habitat._--South Pacific, Station 297, depth 1775 fathoms.


2. _Clathrospyris pyramidalis_, n. sp. (Pl. 95, fig. 9).

Shell four-sided pyramidal, truncate, thorny, with a slight sagittal
stricture. Pores very large, polygonal roundish. Two pairs of large pores
on each side of the ring (at the frontal and the occipital plate). Lateral
pores more numerous. Basal plate with four large pores. The four edges of
the pyramid are prolonged into four short pyramidal divergent lateral feet
(one-third as {1053}long as the shell). Caudal foot short. Horn at the apex
of the truncate pyramid with two lateral teeth.

_Dimensions._--Shell 0.06 long, 0.08 broad; horn and feet 0.02 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


3. _Clathrospyris fusiformis_, n. sp.

Shell nearly cubical, smooth, with slight sagittal stricture. Pores
roundish; three pairs of larger pores on each side of the ring. Basal plate
with six large pores. Five feet of equal length, slender, spindle-shaped,
about as long as the shell, divergent. Apical horn conical, and half as
long as the feet.

_Dimensions._--Shell 0.08 long, 0.09 broad; horn 0.05 long, feet 0.1 long.

_Habitat._--Fossil in Barbados.



Genus 457. _Aegospyris_,[75] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with five basal feet and three coryphal horns.

The genus _Aegospyris_ differs from the preceding _Clathrospyris_, its
ancestral form, in the possession of three horns on the coryphal face (one
odd apical, and two paired frontal horns on each side), and therefore bears
to the latter the same relation that _Triceraspyris_ does to _Tripospyris_,
and _Liriospyris_ to _Hexaspyris_.


1. _Aegospyris aequispina_, n. sp.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores
subregular circular. Basal plate with four large collar pores. Three horns
and five feet all of equal size and similar form, slender conical, slightly
curved, widely divergent, about as long as the shell.

_Dimensions._--Shell 0.08 long, 0.11 broad; horns and feet 0.08 long.

_Habitat._--Central Pacific, Stations 265 to 274, depth 2350 to 2925
fathoms.


2. _Aegospyris octospina_, n. sp.

Shell nearly cubical, smooth, with slight sagittal stricture. Pores
subregular circular; two pairs of larger pores on each side of the ring.
Basal plate with four large pores. Two paired horns and four paired feet of
equal size and similar form, S-shaped curved, twice as long as the shell.
Odd horn and odd feet half as long, straight, conical.

_Dimensions._--Shell 0.08 long, 0.09 broad; six paired spines 0.2 long, two
odd spines 0.1 long.

_Habitat._--South Atlantic, Station 323, depth 1900 fathoms.


{1054}3. _Aegospyris longibarba_, Haeckel.

  _Ceratospyris longibarba_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xxi. figs. 1, 2.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores
subregular circular. Basal plate with four larger central, and eight
smaller peripheral pores. Apical horn and caudal foot short, straight,
conical; two frontal horns longer, curved; four paired feet slender,
curved, twice as long as the shell.

_Dimensions._--Shell 0.06 long, 0.08 broad; paired horns 0.03 long, paired
feet 0.1 long.

_Habitat._--Fossil in Barbados.


4. _Aegospyris aegoceras_, n. sp. (Pl. 95, fig. 10).

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores
irregular roundish. Basal plate with three large pores. Apical horn and
caudal foot short, straight, spindle-shaped; two frontal horns as long as
the shell, strongly curved; four paired feet also curved, at the distal end
forked, divergent; the tergal thinner and as long as the shell, the
pectoral thicker and twice as long.

_Dimensions._--Shell 0.07 long, 0.09 broad; pectoral feet 0.1 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


5. _Aegospyris caprina_, n. sp. (Pl. 86, fig. 8).

Shell nut-shaped, papillate, with sharp sagittal stricture. Pores irregular
roundish, two pairs of larger pores on each side of the ring. Basal plate
with six large pores. Eight spines all straight, subvertical and nearly
parallel, cylindro-conical. Two frontal horns and two tergal feet about as
long as the shell; odd horn shorter; odd foot longer. Two pectoral feet
twice as long as the shell, club-shaped, with a spinulate knob at the
distal end.

_Dimensions._--Shell 0.06 long, 0.09 broad; pectoral feet 0.11 long.

_Habitat._--Central Pacific, Station 271, surface.



Genus 458. _Pentaspyris_,[76] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with five basal feet, without apical horn.

The genus _Pentaspyris_ differs from the two preceding genera in the
absence of any coryphal horn, and represents therefore the pentapodal form
among the hornless Zygospyrida.


1. _Pentaspyris pentacantha_, n. sp. (Pl. 95, fig. 11).

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores
irregular roundish, two pairs of larger pores on each side of the ring.
Basal plate with four larger pores. All five feet {1055}cylindrical,
S-shaped curved, strongly divergent, with few short branches, the two
pectoral feet twice as long as the shell and the two tergal feet; odd
caudal foot shorter.

_Dimensions._--Shell 0.08 long, 0.13 broad; pectoral feet 0.2 long, tergal
feet 0.1, caudal foot 0.06.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Pentaspyris isacantha_, n. sp.

Shell subspherical, smooth, with slight sagittal stricture. Pores small,
regular circular. Basal plate with six large pores (?). All five feet
equal, cylindrical, C-shaped curved, slightly divergent, about as long as
the shell.

_Dimensions._--Shell 0.08 long, 0.09 broad; feet 0.07 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Subfamily 6. THEROSPYRIDA, Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# tetrapoda with two pairs of descending basal
feet, one pair corresponding to the anterior or pectoral, the other pair to
the posterior or tergal feet of the Hexaspyrida.



Genus 459. _Zygospyris_,[77] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with two pairs of lateral feet and an apical
horn.

The genus _Zygospyris_ and the following three genera represent together
the peculiar subfamily of Therospyrida. These always possess four basal
feet, like the Tetraspyrida; but whilst in the latter group two feet are
sagittal, and two lateral, in the Therospyrida there are no sagittal feet
at all, but the four feet are opposed in two lateral pairs; the anterior
pair corresponds to the pectoral, the posterior to the tergal feet of the
Hexaspyrida and Pentaspyrida; from these latter the Therospyrida have been
derived by loss of the sagittal feet.


1. _Zygospyris quadrupes_, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores
irregular roundish, on each side of the ring two pairs of larger pores.
Apical horn conical, straight. Four feet equal, straight, divergent,
conical, about as long as the shell and the horn.

_Dimensions._--Shell 0.08 long, 0.11 broad; horn and feet 0.1 long.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.


{1056}2. _Zygospyris equus_, n. sp. (Pl. 83, fig. 16).

Shell subspherical, rough, with slight sagittal stricture. Pores small and
numerous, subregular circular; no larger annular pores. Apical horn
cylindrical, half as long as the shell. Two pectoral feet somewhat smaller
than the two tergal feet, about as long as the shell, slightly divergent,
cylindrical. The distal ends of the feet and of the horn form an ovate,
dimpled and spinulate cone.

_Dimensions._--Shell 0.06 long, 0.09 broad; horn 0.04 long, feet 0.06 long.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



Genus 460. _Elaphospyris_,[78] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with two pairs of lateral feet and three
coryphal horns.

The genus _Elaphospyris_ differs from the preceding _Zygospyris_, its
ancestral form, in the possession of three coryphal horns (one odd apical
and two paired frontal horns), and therefore bears to it the same relation
that _Triceraspyris_ does to _Tripospyris_ among the Tripospyrida.



Subgenus 1. _Giraffospyris_, Haeckel, 1881, Prodromus, p. 442.

_Definition._--Feet simple, not branched nor forked.


1. _Elaphospyris heptaceros_, Haeckel.

  _Ceratospyris heptaceros_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 2.

  _Giraffospyris heptaceros_, Haeckel, 1881, Prodromus, p. 442.

Shell nut-shaped, tuberculate, with slight sagittal stricture and
subregular circular pores. Basal plate with four large pores. Apical horn
small, conical, shorter than the two curved lateral horns, which are as
long as the shell. Caudal and sternal feet small, conical, straight. Two
pectoral feet slender, divergent, S-shaped, about as long as the shell.

_Dimensions._--Shell 0.05 long, 0.07 broad; horns and feet 0.02 to 0.08
long.

_Habitat._--Fossil in Barbados.


2. _Elaphospyris capricornis_, n. sp.

Shell nut-shaped, spiny, with slight sagittal stricture and numerous small
circular pores. Basal plate with four large pores. Three horns slender,
simple, about as long as the shell, the middle one straight, the two
lateral curved. Four feet of nearly equal size, slender, curved, divergent,
simple, twice as long as the shell and the horns.

_Dimensions._--Shell 0.07 long, 0.09 broad; horns 0.08 long, feet 0.15
long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



{1057}Subgenus 2. _Corythospyris_, Haeckel, 1881, Prodromus, p. 443.

_Definition._--Feet branched or forked.


3. _Elaphospyris damaecornis_, n. sp. (Pl. 84, fig. 10).

Shell flat and broad, nearly triangular, with slight sagittal stricture and
irregular roundish pores; two very large pores on the frontal and on the
occipital face, opposite on both edges of the broad sagittal ring. Basal
plate with four large central and several smaller lateral pores. Three
horns about half as long as the shell, with two to six irregular branches.
Four feet of equal size, about as long as the shell, divergent, forked,
with four to six irregular terminal branches. (The shell in fig. 10 is seen
from the apical side.)

_Dimensions._--Shell 0.09 long, 0.13 broad; horns 0.05 long, feet 0.1 long.

_Habitat._--Indian Ocean, Cocos Islands, Rabbe, surface.


4. _Elaphospyris cervicornis_, n. sp. (Pl. 86, fig. 13).

Shell polyhedral, spiny, with deep sagittal stricture and a small number of
large roundish pores; two pairs of large pores on each side of the ring.
Basal plate with four pores. Three large horns as long as the shell arise
from the apex between smaller conical spines; the middle odd horn simple,
the two lateral each with a pair of branches. Two pectoral feet very large,
divergent, with broad and irregular distal ramification, twice as long as
the shell and as the two tergal feet, which are less branched. (Fig. 13
exhibits the shell from the dorsal side.)

_Dimensions._--Shell 0.09 long, 0.11 broad; horns and smaller feet 0.07 to
0.09 long; pectoral feet 0.16 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


5. _Elaphospyris alcicornis_, n. sp. (Pl. 86, fig. 12).

Shell nut-shaped, spiny, with sharp sagittal stricture and large roundish
pentagonally framed pores; three pairs of larger pores on each side of the
ring. Basal plate with four larger and four alternate smaller pores. There
arise from the apex, between smaller spines, three large, divergent,
pyramidal horns, which are nearly as long as the shell, and connected by an
arched frontal bridge. Two pectoral feet very large, divergent, prismatic,
longer than the shell, and at the distal end with a bunch of thick spines.
Two tergal feet half as long and thick, simple (in the figure hidden behind
the large pectoral feet).

_Dimensions._--Shell 0.09 long, 0.11 broad; horns and smaller feet 0.06
long, pectoral feet 0.12 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



{1058}Genus 461. _Taurospyris_,[79] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with two pairs of lateral feet and one pair of
lateral horns.

The genus _Taurospyris_ bears only two frontal horns in the coryphal face
of the shell, and may therefore be derived from the preceding closely
allied _Elaphospyris_ by reduction and loss of the middle or apical horn.


1. _Taurospyris cervina_, n. sp. (Pl. 95, fig. 12).

Shell nut-shaped, thorny, with deep sagittal stricture and irregular
roundish pores; three pairs of larger pores on each side of the ring. Basal
plate with four large pores. Two horns cylindrical, curved, widely
divergent, about as long as the shell, branched. Four feet of nearly equal
length, also cylindrical and curved, divergent, somewhat longer than the
shell, in the distal half branched like a deer's antler.

_Dimensions._--Shell 0.07 long, 0.11 broad; horns 0.03 long, feet 0.06
long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms; also fossil in
Barbados.


2. _Taurospyris bovina_, n. sp.

Shell subspherical, smooth, with slight sagittal stricture and small
circular pores. Basal plate with six larger pores. Two horns conical,
curved, divergent, about as long as the shell. Two pectoral feet very
large, twice as long as the shell and as the two thinner tergal feet; all
four feet curved, cylindrical, divergent, pointed at the distal end.

_Dimensions._--Shell 0.08 long, 0.09 broad; horns and posterior feet 0.1,
anterior feet 0.2 long.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



Genus 462. _Therospyris_,[80] Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# with two pairs of lateral feet, without apical
horn.

The genus _Therospyris_ has two pairs of lateral feet corresponding to
those of the preceding three genera, but differs from them in the complete
absence of horns on the coryphal face of the shell.


1. _Therospyris canis_, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores
irregular, roundish. Basal plate with four longer pores. Surface covered
with roundish tubercles. Four feet equal, divergent, about as long as the
shell, thickened at the distal end, club-shaped, not forked.

_Dimensions._--Shell 0.07 long, 0.11 broad; feet 0.09 long.

_Habitat._--Fossil in Barbados.


{1059}2. _Therospyris felis_, n. sp. (Pl. 89, fig. 6).

Shell nut-shaped, mammillate, with sharp sagittal stricture. Pores large,
irregularly roundish or polygonal, of somewhat different size. Basal plate
with four large pores. Surface covered with hemispherical pointed mammillæ.
Four feet equal, divergent, half as long as the shell, at the distal end
forked, with few small branches.

_Dimensions._--Shell 0.1 long, 0.15 broad; feet 0.05 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Therospyris leo_, n. sp. (Pl. 89, fig. 5).

Shell nearly cubical, papillate, with slight sagittal stricture. Pores
irregular, roundish; on each side of the ring three pairs of larger pores
(the undermost the largest). Basal plate with two large pores. Surface
covered with conical papillæ. Four feet equal, divergent, about as long as
the shell, with an external spur in the middle, and irregularly branched
spines at the distal end.

_Dimensions._--Shell 0.08 long, 0.12 broad; feet 0.09 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



Subfamily 7. POLYSPYRIDA, Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Zygospyrida# polypoda, with numerous descending basal feet
(at least seven to nine, usually twelve to sixteen or more).



Genus 463. _Petalospyris_,[81] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.

_Definition._--#Zygospyrida# with numerous (seven to twelve or more) basal
feet and one apical horn.

The genus _Petalospyris_ and the following three genera form together the
peculiar subfamily of Polyspyrida, differing from the other Zygospyrida in
the multiplication of the radial feet, which descend from the basal face of
the shell; they may therefore be also called "Zygospyrida multiradiata,"
and bear the closest relationship to the Archiphænida (or the "Monocyrtida
multiradiata"). They differ, however, from the latter in the presence of
the distinct sagittal stricture, characteristic of all #Spyroidea#. The
number of the basal feet, which form a coronet around the margin of the
basal plate, is commonly between twelve and sixteen, but often more. Their
form is usually flat, lamellar, but often also more or less cylindrical or
conical.



{1060}Subgenus 1. _Petalospyrantha_, Haeckel.

_Definition._--Basal plate with two large collar pores only, separated by
the base of the primary ring.


1. _Petalospyris foveolata_, Ehrenberg.

  _Petalospyris foveolata_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig.
  14; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 80, Taf. xxii. fig.
  10.

Shell campanulate, smooth, with distinct sagittal stricture and subregular
circular pores. Basal plate with two large collar pores only. Apical horn
and the eight feet slender, conical, slightly curved, about as long as the
shell; feet somewhat divergent (often seven or nine instead of eight).

_Dimensions._--Shell diameter 0.04 to 0.05; length of the horn and the feet
0.04 to 0.05.

_Habitat._--Fossil in Barbados.


2. _Petalospyris floscula_, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture and subregular
circular pores. Basal plate with two large triangular pores only. Apical
horn slender, conical, twice as long as the shell. Twelve to sixteen feet
flattened, leaf-shaped, broad, slightly divergent, as long as the shell,
with truncate distal end.

_Dimensions._--Shell 0.06 long, 0.09 broad; horn 0.12 long, feet 0.05 to
0.07 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



Subgenus 2. _Petalospyrella_, Haeckel.

_Definition._--Basal plate with three large collar pores (two paired
posterior cardinal, and an odd anterior sternal pore).


3. _Petalospyris triomma_, n. sp. (Pl. 87, fig. 14).

Shell nut-shaped, tuberculate, with sharp sagittal stricture and irregular
roundish pores. Basal plate with three large pores and three alternate
smaller. Apical horn stout, conical, half as long as the shell. Twelve to
fifteen feet, divergent, curved, pointed, as long as the horn.

_Dimensions._--Shell 0.06 long, 0.08 broad; horn and feet 0.03 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


4. _Petalospyris platyacantha_, Ehrenberg.

  _Petalospyris platyacantha_, Ehrenberg, Abhandl. d. k. Akad. d. Wiss.
  Berlin, 1875, p. 80, Taf. xxii. fig. 8.

Shell campanulate, smooth, with slight sagittal stricture and small
irregular roundish pores. Basal plate with three large pores (?). Apical
horn very strong, three-sided pyramidal, twice as {1061}long as the shell
(its edge is described by Ehrenberg as a "canaliculus.") Feet ten to
twelve, flat, triangular, vertical, about as long as the shell.

_Dimensions._--Shell 0.04 long, 0.05 broad; 0.07 long, feet 0.03 long.

_Habitat._--Fossil in Barbados.


5. _Petalospyris corona_, Stöhr.

  _Petalospyris corona_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 98, Taf.
  iii. fig. 13.

Shell nut-shaped, smooth, with slight sagittal stricture and very numerous
small circular pores; on each side of the stricture three larger annular
pores (the undermost the largest). Basal plate with three large pores only.
Apical horn very small, conical. Feet twelve to eighteen, short conical,
nearly vertical, shorter than the half shell (in my specimen from
Caltanisetta much stouter than in that of Stöhr).

_Dimensions._--Shell 0.07 long, 0.09 broad; horn and feet 0.01 to 0.03
long.

_Habitat._--Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).



Subgenus 3. _Petalospyrissa_, Haeckel.

_Definition._--Basal plate with four collar pores (two larger posterior
cardinal and two smaller anterior jugular pores).


6. _Petalospyris octopus_, n. sp. (Pl. 87, fig. 11).

Shell nut-shaped, tuberculate, with sharp sagittal stricture and irregular,
roundish pores. Basal plate with four larger pores. Horn slender, conical,
half as long as the shell. Feet eight, very slender, about three times as
long as the shell, subvertical, with outer convex edge and convergent ends.

_Dimensions._--Shell 0.06 long, 0.09 broad; horn 0.03 long, feet 0.2 long.

_Habitat._--Tropical Atlantic, Station 342, depth 1445 fathoms.


7. _Petalospyris eupetala_, Ehrenberg.

  _Petalospyris eupetala_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. xxii. fig. 4.

Shell nut-shaped, tuberculate, with slight sagittal stricture and scattered
small circular pores. Basal plate with four large collar pores (sometimes
surrounded by several small peripheral pores). Apical horn slender,
conical, as long as the shell. Feet sixteen to twenty, laminated and
truncate, of the same length, nearly vertical and parallel.

_Dimensions._--Shell 0.06 long, 0.08 broad; horn and feet 0.05 to 0.07
long.

_Habitat._--Fossil in Barbados.


{1062}8. _Petalospyris anthemis_, n. sp.

Shell nut-shaped, spinulate, with deep sagittal stricture and irregular,
roundish pores. Basal plate with four large pores of equal size. Apical
horn conical, twice as long as the shell. Feet twenty to thirty, laminated
and truncate, as long as the shell, divergent.

_Dimensions._--Shell 0.05 long, 0.08 broad; horn 0.1 long, feet 0.6 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


9. _Petalospyris tessaromma_, n. sp.

Shell subspherical, with slight sagittal stricture and few small pores; on
each side of the stricture four larger, square, annular pores. Basal plate
with four large collar pores (two larger cardinal and two smaller jugular
pores). Horn and feet conical, about half as long as the shell. Feet twenty
to twenty-five, slightly curved, convergent.

_Dimensions._--Shell diameter 0.08; horn and feet 0.04.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms; also fossil
in Barbados.



Subgenus 4. _Petalospyromma_, Haeckel.

_Definition._--Basal plate with numerous (six or more) collar pores,
commonly three or four larger central, and six to twelve smaller peripheral
pores.


10. _Petalospyris novena_, n. sp. (Pl. 83, fig. 12).

Shell nut-shaped, tuberculate, with slight sagittal stricture and
irregular, roundish pores. Basal plate with nine pores (three large primary
and three alternate pairs of small secondary pores). Nine long
corresponding feet, twice to four times as long as the shell (three very
thick primary, and three alternate pairs of thin secondary feet). All feet
cylindrical, curved, widely divergent. Horn conical.

_Dimensions._--Shell 0.06 long, 0.08 broad; horn and feet 0.15 to 0.25.

_Habitat._--Indian Ocean (Cocos Islands), Rabbe, surface.


11. _Petalospyris argiscus_, Ehrenberg.

  _Petalospyris argiscus_, Ehrenberg, 1875, Abhandl. d. k. Akad. Wiss.
  Berlin, p. 80, Taf. xxii. figs. 1, 2.

  _Petalospyris argiscus_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. p. 539, Taf. xxxii. fig. 17, _a_, _b_.

Shell nut-shaped, tuberculate, with slight sagittal stricture and
irregular, roundish pores. Basal plate with nine pores (three larger
central and three alternate pairs of smaller peripheral pores).
{1063}Apical horn slender, spindle-shaped, about as long as the shell.
Twenty to twenty-five feet, of the same length, broad, lamellar and
truncate, nearly vertical, slightly divergent.

_Dimensions._--Shell 0.06 long, 0.1 broad; horn and feet 0.05 to 0.07 long.

_Habitat._--Fossil in Barbados.


12. _Petalospyris papillata_, n. sp.

Shell nearly cubical, papillate, without external sagittal stricture, with
small, irregular, roundish pores. Basal plate with six pores (three larger
and three alternate smaller). Apical horn conical, half as long as the
shell. Feet twenty to thirty, one-half to one-third as long, conical,
divergent.

_Dimensions._--Shell diameter 0.09; horn 0.04 long, feet 0.03 to 0.05 long.

_Habitat._--North Atlantic, Station 353, depth 2965 fathoms.


13. _Petalospyris dictyocubus_, n. sp. (Pl. 86, fig. 6).

Shell nearly cubical, smooth, without external stricture, but with a
complete, parietal, square, sagittal ring. On each side of the ring four
pairs of larger pores, whilst the lateral pores are smaller and more
numerous. Basal plate also with four pairs of larger pores and smaller
lateral pores. Apical horn and basal feet short, pyramidal, scarcely
one-fourth as long as the shell. The three primary feet are larger than the
six to nine secondary feet.

_Dimensions._--Shell diameter 0.08; horn and feet 0.02 long.

_Habitat._--Central Pacific, Station 274, surface.


14. _Petalospyris bellidiastrum_, n. sp.

Shell nut-shaped, tuberculate, with slight sagittal stricture and
irregular, roundish pores. Basal plate with twelve pores (four central
larger and eight peripheral smaller pores). Apical horn slender, conical,
about as long as the shell (sometimes ramified at the distal end). Feet
sixteen to twenty, broadly lamellar, truncate, divergent, about as long as
the shell.

_Dimensions._--Shell 0.08 long, 0.1 broad; horn and feet 0.07 to 0.09 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; also fossil
in Barbados.


15. _Petalospyris dinoceras_, n. sp. (Pl. 87, fig. 12).

Shell nut-shaped, mammillate, without external stricture, but with complete
external sagittal ring. Pores subregular, circular. Basal plate with four
large central pores, surrounded by a circle of twelve to twenty small
peripheral pores. Apical horn very large, spindle-shaped, one and a half
times as long as the shell. Feet twenty-five to thirty, broadly lamellar,
truncate, divergent, about as long as the shell.

_Dimensions._--Shell 0.11 long, 0.13 broad; horn 0.15 long, feet 0.09 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


{1064}16. _Petalospyris furcata_, n. sp.

Shell nut-shaped, smooth, with sharp sagittal stricture. Pores numerous,
small, and circular; no larger annular pores. Basal plate with four larger
and four alternate pairs of smaller pores. Horn conical, about as long as
the shell. Feet fifteen to twenty, broadly lamellar, about twice as long as
the shell, in the distal half forked.

_Dimensions._--Shell 0.04 long, 0.06 broad; horn 0.05 long, feet 0.1 long.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


17. _Petalospyris lobata_, n. sp. (Pl. 87, fig. 13).

Shell subspherical, smooth, with slight sagittal stricture. Pores small,
roundish; on each side of the ring two pairs of larger annular pores. Basal
plate with four pores. Horn stout, three-sided prismatic, half as long as
the shell. Feet twelve to sixteen, lamellar, lobate (the most part with
three lobes), nearly vertical, about as long as the shell.

_Dimensions._--Shell diameter 0.05; horn 0.03, feet 0.05 long.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.



Genus 464. _Anthospyris_,[82] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Zygospyrida# with numerous (seven to nine or more) basal
feet and three coryphal horns.

The genus _Anthospyris_ differs from the preceding _Petalospyris_, its
ancestral form, in the possession of three horns on the coryphal face (one
odd middle apical horn and two paired frontal horns, one on each side). The
former therefore bears to the latter the same relation that _Triceraspyris_
does to _Tripospyris_ and _Liriospyris_ to _Hexaspyris._


1. _Anthospyris mammillata_, n. sp. (Pl. 87, fig. 16).

Shell nut-shaped, mammillate, with deep sagittal stricture and irregular,
polygonal pores. Basal plate with two large ovate pores (?). The pediculate
apical horn and the two frontal horns stout and short, conical, twice to
three times as large as the conical papillæ of the surface. Feet twelve to
fifteen, lanceolate lamellar, pointed, divergent, about as long as the
shell.

_Dimensions._--Shell 0.05 long, 0.08 broad; horns 0.03, feet 0.04 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


{1065}2. _Anthospyris spathulata_, n. sp. (Pl. 87, fig. 15).

Shell subspherical, thorny, with slight sagittal stricture and irregular,
roundish pores. Basal plate with three large pores. The three horns
spindle-shaped, half as long as the ten to twelve thin feet, which are
pediculate, shovel-shaped, a little divergent, and shorter than the shell.

_Dimensions._--Shell 0.05 diameter; horn 0.02 long, feet 0.04 long.

_Habitat._--North Pacific, Station 250, depth 3050 fathoms.


3. _Anthospyris diaboliscus_, Haeckel.

  _Petalospyris diaboliscus_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig.
  12; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 80, Taf. xxii. fig. 3.

Shell nut-shaped, smooth, with slight sagittal stricture and small circular
pores. Basal plate with four large pores. Apical horn straight conical,
frontal horns curved laterally. Feet nine to twelve, of about the same
length as the horns and the shell, broad lamelliform, truncate, nearly
vertical, slightly curved.

_Dimensions._--Shell 0.04 long, 0.07 broad; horns and feet 0.05 to 0.07
long.

_Habitat._--Fossil in Barbados.


4. _Anthospyris arachnoides_, Haeckel.

  _Petalospyris arachnoides_, Haeckel, 1862, Monogr. d. Radiol., p. 294,
  Taf. xii. fig. 7.

Shell nut-shaped, tuberculate, with slight sagittal stricture and
irregular, polygonal pores. Basal plate with four large pores (?). Apical
horn straight, conical, longer than the two curved lateral horns. Feet ten,
slender, S-shaped, widely divergent, about as long as the shell is broad.

_Dimensions._--Shell 0.05 long, 0.08 broad; horns 0.03 to 0.05 long, feet
0.08 long.

_Habitat._--Mediterranean (Messina), Atlantic, Station 354, surface.


5. _Anthospyris aculeata_, n. sp. (Pl. 86, fig. 5).

Shell campanulate, spiny, with deep sagittal stricture and irregular,
roundish pores. On each side of the stricture three pairs of larger annular
pores. Basal plate with two large square pores. The three horns of the same
size as, and similar form to, the ten to fifteen feet, slender pyramidal,
straight, divergent, about half as long as the shell. (This species is very
variable and closely allied to _Ceratospyris_.)

_Dimensions._--Shell diameter 0.08 to 0.12; horns and feet 0.04 to 0.06
long.

_Habitat._--Central Pacific, Stations 266 to 274, surface.


6. _Anthospyris doronicum_, n. sp. (Pl. 87, fig. 18).

Shell nut-shaped, spiny, with a deep sagittal stricture and small circular
pores. On each side of the stricture two pairs of very large square annular
pores. Basal plate with four larger collar {1066}pores and a corona of
numerous small peripheral pores. Three horns spindle-shaped, divergent,
about half as long as the shell. Feet twenty-five to thirty, broad,
lamellar, lanceolate, pointed, divergent, nearly as long as the shell.

_Dimensions._--Shell 0.1 long, 0.13 broad; horns 0.06, feet 0.09 long.

_Habitat._--South Pacific, Station 296, depth 1825 fathoms.


7. _Anthospyris tragopogon_, n. sp. (Pl. 87, fig. 17).

Shell nut-shaped, tuberculate, with distinct sagittal stricture and small
regular circular pores. Basal plate with numerous small pores. Apical horn
very large, spindle-shaped, twice as long as the shell; frontal horns
small, scarcely one-fourth as long, curved laterally. Feet twenty-five to
thirty, three to four times as long as the shell, lamellar, lanceolate,
pointed, parallel, vertical.

_Dimensions._--Shell 0.08 long, 0.11 broad; apical horn 0.16, feet 0.2
long.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.



Genus 465. _Ceratospyris_,[83] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.

_Definition._--#Zygospyrida# with numerous (seven to twelve or more) basal
feet and numerous coryphal horns.

The genus _Ceratospyris_ differs from all the other Zygospyrida in the
possession of numerous large spines on the surface of the shell, which
usually exhibits only a small number of large pores or meshes. The lower
spines which cover the inferior or basal face of the shell (usually nine to
twelve or more) may be compared to the descending "basal feet" of the other
Zygospyrida; the upper spines, however, which cover the superior or
coryphal face (usually six to nine, rarely more), may be regarded as
"coryphal horns." In many species of this genus the lattice-work of the
shell is of a peculiar loose kind, with few large meshes, resembling the
wicker-work of the Plectanida.



Subgenus 1. _Lophospyris_, Haeckel, 1881, Prodromus, p. 443.

_Definition._--Spines simple, not branched. Meshes of the shell usually
polygonal, or roundish with polygonal frames. Bars of the network
prismatic.


1. _Ceratospyris polygona_, n. sp. (Pl. 86, fig. 1).

Shell polyhedral, with deep sagittal stricture, studded with twenty-four to
thirty long simple straight slender pyramidal spines, which are as long as
the shell or longer. All pores large, polygonal. On the frontal and the
occipital face two pairs of very large pores only, the superior
{1067}pentagonal, larger than the inferior tetragonal. Basal plate with two
triangular pores. Bars of the loose framework three-sided prismatic, thin.

_Dimensions._--Shell 0.08 long, 0.12 broad; spines 0.06 to 0.12 long.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface.


2. _Ceratospyris pentagona_, Ehrenberg.

  _Ceratospyris pentagona_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. x. fig. 15.

Shell polyhedral, with slight sagittal stricture, studded with twenty-four
to thirty small simple conical spines, which are shorter than one-fourth of
the shell. Most pores pentagonal. On the frontal and the occipital face two
pairs of large pores only, the superior smaller than the inferior. Basal
plate with four quadrangular pores. Bars of the network prismatic, thin.

_Dimensions._--Shell 0.07 long, 0.11 broad; spines 0.01 to 0.02 long.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface.


3. _Ceratospyris allmersii_, n. sp. (Pl. 86, fig. 3).

Shell polyhedral, with slight sagittal stricture, studded with thirty to
forty prismatic spines which are not longer than half the shell. Most pores
pentagonal. On the frontal face two, on the occipital three pairs of larger
pores; the inferior the largest. Basal plate with two rhomboidal pores (?).
Bars of the network three-sided prismatic, thin. Dedicated to my dear
friend, the excellent poet and naturalist, Hermann Allmers, of
Rechtenfleth.

_Dimensions._--Shell 0.08 long, 0.12 broad; spines 0.01 to 0.03.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


4. _Ceratospyris mulderi_, n. sp. (Pl. 86, fig. 4).

Shell polyhedral, with deep sagittal stricture, studded with fifty to
seventy prismatic spines; two inferior (pectoral) spines about as long as
the shell, the others much shorter. Pores polygonal. On the frontal and the
occipital face one pair of very large pores. Basal plate with two
distinctly hexagonal pores. Bars of the loose network prismatic. Dedicated
to my dear friend, the excellent author and painter, Ludwig Mulder, of the
Hague.

_Dimensions._--Shell 0.07 long, 0.12 broad; spines 0.01 to 0.08.

_Habitat._--Indian Ocean, Sunda Straits (Rabbe), surface.


5. _Ceratospyris strasburgeri_, n. sp. (Pl. 86, fig. 2).

Shell polyhedral, with slight sagittal stricture, studded with thirty to
forty prismatic spines, which are about half as long as the shell (two or
four inferior are longer). Pores roundish, with polygonal frames. On the
frontal and occipital face two pairs of larger pores (the superior
{1068}smaller). Basal plate with two large pentagonal pores. Bars of the
network prismatic. Dedicated to my dear friend, the celebrated botanist,
Professor Eduard Strasburger, of Bonn.

_Dimensions._--Shell 0.07 long, 0.1 broad; spines 0.02 to 0.04.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475.


6. _Ceratospyris mülleri_, Stöhr.

  _Ceratospyris mülleri_, Stöhr, 1880, Palæontogr., vol. xxvi. Taf. iii.
  fig. 15.

Shell polyhedral, with slight collar stricture, studded with forty to fifty
pyramidal spines, shorter than half the shell. Pores circular, with
pentagonal frames of the same breadth, all nearly of equal size. (Basal
plate with four pores?) Bars of the network prismatic. Dedicated to
Johannes Müller.

_Dimensions._--Shell 0.08 long, 0.1 broad; spines 0.01 to 0.03.

_Habitat._--Fossil in Tertiary rocks of Sicily, Grotte (Stöhr).


7. _Ceratospyris krausei_, n. sp. (Pl. 86, fig. 10).

Shell nut-shaped, with deep sagittal stricture, studded with forty to fifty
strong conical spines; six basal spines as long as the shell and two to
three times as long as the others. Pores roundish polygonal, twice to three
times as broad as the bars; two pairs of larger pores on each side of the
ring. (Basal plate with four large pores?) Bars of the network rounded,
thick. Dedicated to my dear friend, the excellent author, Ernst Krause
(Carus Sterne), of Berlin.

_Dimensions._--Shell 0.06 long, 0.09 broad; spines 0.03 to 0.08.

_Habitat._--Western Tropical Pacific (Philippine Sea), Station 206, depth
2100 fathoms.


8. _Ceratospyris preyeri_, n. sp. (Pl. 86, fig. 9).

Shell nut-shaped, with slight sagittal stricture, studded with ten to
twelve longer club-shaped spines (about as long as the shell) and numerous
smaller conical spines. Pores irregular, roundish, numerous; two pairs of
larger pores on each side of the ring. Basal plate with four large pores.
Bars of the network rounded. Dedicated to my honoured friend and colleague,
the celebrated investigator of psychical ontogeny, Professor William
Preyer, of Jena.

_Dimensions._--Shell 0.07 long, 0.09 broad; spines 0.02 to 0.08 long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


9. _Ceratospyris echinus_, Ehrenberg.

  _Ceratospyris echinus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx, fig. 12.

Shell subspherical, with slight sagittal stricture, studded with numerous
conical curved spines; six basal and one apical spine are larger than the
others, about as long as the shell. Pores numerous, small, circular. Basal
plate with numerous pores. Bars of the network roundish.

_Dimensions._--Shell 0.05 long, 0.06 broad; spines 0.02 to 0.05 long.

_Habitat._--Fossil in Barbados.



{1069}Subgenus 2. _Cladospyris_, Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.

_Definition._--Spines forked or branched. Meshes roundish or polygonal.


10. _Ceratospyris ramosa_, Ehrenberg.

  _Ceratospyris ramosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. xx. fig. 7.

  _Cladospyris ramosa_, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d.
  Wiss. Berlin, p. 54.

Shell nut-shaped, with slight sagittal stricture, studded with numerous
conical, irregularly branched spines. The largest about as long as the
shell. Pores irregular, roundish; on each side of the ring two pairs of
larger pores. Basal plate with four pores. Bars of the network roundish.

_Dimensions._--Shell 0.06 long, 0.08 broad; spines 0.02 to 0.08 long.

_Habitat._--Fossil in Barbados.


11. _Ceratospyris carnerii_, n. sp. (Pl. 86, fig. 11).

Shell nut-shaped, with sharp sagittal stricture, studded with numerous
pyramidal spines; two basal spines are larger, as long as the shell, and
irregularly branched. Pores polygonal; on each side of the ring three pairs
of larger pores. Basal plate with four large pores. Dedicated to my dear
friend, the excellent monistic philosopher, B. von Carneri.

_Dimensions._--Shell 0.09 long, 0.12 broad; spines 0.02 to 0.08 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


12. _Ceratospyris calorrhiza_, n. sp. (Pl. 87, fig. 19).

Shell nut-shaped, with deep sagittal stricture, studded with numerous
conical strong spines, about one-fourth as long as the shell. Basal spines
irregularly branched, with root-like ends. Pores irregular, roundish, some
larger pores on each side of the ring. Basal plate with four larger pores.
Bars of the network roundish.

_Dimensions._--Shell 0.1 long, 0.14 broad; spines 0.02 to 0.04 long.

_Habitat._--Central Pacific, Station 271, surface.



Genus 466. _Gorgospyris_,[84] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Zygospyrida# with numerous (seven to twelve or more) basal
feet, without coryphal horns.

The genus _Gorgospyris_ agrees with the three preceding genera in the
possession of numerous basal feet, but differs from them in the complete
absence of any horns on the coryphal face. It represents therefore the
"hornless polypedal Zygospyrida," and may {1070}be derived from
_Petalospyris_ by loss of the original apical horn. The feet are commonly
numerous, and often form a circle around the margin of the basal plate,
similar to the circle of tentacles in many Medusæ (Gorgon).



Subgenus 1. _Gorgospyrium_, Haeckel.

_Definition._--Feet simple, not branched.


1. _Gorgospyris medusa_, n. sp. (Pl. 87, fig. 1).

Shell hemispherical, papillate, with slight sagittal stricture and
subregular circular pores. Basal plate with three large collar pores (by
mistake not correctly represented in the figure). Ten to twelve slender
feet, twice as long as the shell, strongly curved and divergent, of equal
length.

_Dimensions._--Shell 0.06 long, 0.08 broad; feet 0.1 long.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


2. _Gorgospyris medusetta_, n. sp. (Pl. 87, fig. 2).

Shell misshaped, smooth, with deep sagittal stricture and irregular,
roundish pores. Basal plate with three large collar pores, alternating with
three pairs of smaller pores. Sixteen to twenty slender feet, about as long
as the shell, slightly curved and divergent, of nearly equal length.

_Dimensions._--Shell 0.05 long, 0.08 broad; feet 0.05 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


3. _Gorgospyris ehrenbergii_, Haeckel.

  _Petalospyris pentas_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. xxii. fig. 11.

Shell nut-shaped, smooth, with slight sagittal stricture and unequal
circular pores. Basal plate with three large central pores, alternating
with three pairs of smaller pores, and with a peripheral circle of smaller
pores. Twenty-four to thirty short truncated feet, shorter than half the
shell.

_Dimensions._--Shell 0.05 long, 0.07 broad; feet 0.02 long.

_Habitat._--Fossil in Barbados.


4. _Gorgospyris polypus_, n. sp. (Pl. 87, fig. 3).

Shell hemispherical, papillate, with slight sagittal stricture and
subregular circular pores. Basal plate with four larger and four
alternating smaller pores. Feet sixteen to twenty, slender, carved,
divergent; four primary feet larger, twice to three times as long as the
shell and the other feet.

_Dimensions._--Shell 0.08 long, 0.1 broad; feet 0.1 to 0.2 long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


{1071}5. _Gorgospyris eurycolpos_, n. sp. (Pl. 87, fig. 5).

Shell nut-shaped, rough, with deep sagittal stricture and irregular,
roundish pores; two to three pairs of larger annular pores on each side of
the stricture. Basal plate with four large collar pores. Feet eight, short,
triangular, vertical, about one-fourth as long as the shell.

_Dimensions._--Shell 0.08 long, 0.13 broad; feet 0.02 long.

_Habits._--Central Pacific, Station 270, depth 2925 fathoms.


6. _Gorgospyris liriope_, n. sp. (Pl. 87, fig. 6).

Shell nut-shaped, thorny, with sharp sagittal stricture and irregular,
roundish pores. Two pairs of larger annular pores on each side of the ring.
Basal plate with two very large circular pores only. Eight to ten short
feet vertical, about one-fourth as long as the shell, with an elegant
papillate knob at the distal end.

_Dimensions._--Shell 0.07 long, 0.1 broad; feet 0.02 long.

_Habitat._--South Atlantic, Station 323, depth 1900 fathoms.


7. _Gorgospyris lamellosa_, n. sp.

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate
with four larger and four alternate pairs of smaller pores. Feet fifteen to
twenty-five, broad, lamellar, vertical, truncate, about as long as the
shell, of irregular size and form, very variable.

_Dimensions._--Shell 0.07 long, 0.1 broad; feet 0.05 to 0.1 long.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Thamnospyris_, Haeckel, 1881, Prodromus, p. 443.

_Definition._--Feet divided or branched.


8. _Gorgospyris schizopodia_, n. sp. (Pl. 87, fig. 4).

Shell hemispherical, smooth, with slight sagittal stricture and small
regular, circular pores. Basal plate with four large central and a circle
of small pores. Feet fifteen to twenty, broad, lamellar, confluent at the
base, about as long as the shell, irregularly divided or forked.

_Dimensions._--Shell 0.06 long, 0.08 broad; feet 0.05 to 0.08 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


9. _Gorgospyris thamnopodia_, n. sp.

  _Thamnospyris thamnopodia_, Haeckel, 1881, Prodromus, p. 143.

Shell nut-shaped, tuberculate, with deep sagittal stricture and irregular,
roundish pores. Basal plate with numerous small pores. Feet twenty to
thirty, slender, curved, divergent, twice to three times as long as the
shell, irregularly branched.

_Dimensions._--Shell 0.08 long, 0.12 broad; feet 0.15 to 0.25 long.

_Habitat._--Indian Ocean (Madagascar), Rabbe, surface.



{1072}Subfamily 8. CIRCOSPYRIDA, Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Zygospyrida# apoda, without descending basal feet.



Genus 467. _Circospyris_,[85] Haeckel, 1881, Prodromus, p. 444.

_Definition._--#Zygospyrida# without basal feet, with an apical horn.

The genus _Circospyris_ and the following closely allied genus
_Dictyospyris_ represent together the small subfamily Circospyrida,
differing from all other Zygospyrida in the absence of feet on the basal
face. They have probably arisen from the Tripospyrida (_Tripospyris_) by
reduction and loss of the feet (in the same way as the eradiate #Cyrtoidea#
from the triradiate). But it is also possible that many of the Circospyrida
(if not all) are derived directly from the Semantida (_Clathrocircus_) by
the closing of the two lateral openings and by completing the framework.


1. _Circospyris nucula_, n. sp. (Pl. 95, fig. 13).

Shell nut-shaped, compressed, smooth, with prominent sagittal ring. On each
side of the ring three to four pairs of very large annular polygonal pores.
Lateral pores small and numerous, roundish. Basal plate with two large
pores only. Horn slender, conical, shorter than half the shell.

_Dimensions._--Shell 0.11 long, 0.13 broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


2. _Circospyris gigas_, Haeckel.

  _Dictyospyris gigas_, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, p.
  68, Taf. xix. fig. 6.

Shell nut-shaped, tuberculate, with distinct sagittal stricture. On each
side of the ring four pairs of larger annular pores. Lateral pores
roundish, smaller. Basal plate with four large central and a circle of
eight to twelve smaller peripheral pores. Horn cylindrical, about half as
long as the shell (in the inverted figure of Ehrenberg directed downwards).

_Dimensions._--Shell 0.1 to 0.15 long, 0.15 to 0.2 broad; horn 0.05 to 0.08
long.

_Habitat._--Fossil in Barbados.


3. _Circospyris tridentata_, Haeckel.

  _Dictyospyris tridentata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 70, Taf. xix. fig. 10, _a_, _b_.

Shell nut-shaped, smooth, with sharp sagittal stricture. On each side of
the ring two pairs of large annular pores. Lateral pores roundish, smaller.
Basal plate with six large pores. Horn slender, cylindrical, about as long
as the shell, with three sharp teeth at the distal end.

_Dimensions._--Shell 0.03 long, 0.05 broad; horn 0.03 long.

_Habitat._--Fossil in Barbados.



{1073}Genus 468. _Dictyospyris_,[86] Ehrenberg, 1847, Monatsber. d. k.
preuss. Akad. d. Wiss. Berlin, p. 54.

_Definition._--#Zygospyrida# without basal feet, and without coryphal
horns.

The genus _Dictyospyris_, the last and simplest of the twenty-eight genera
of Zygocyrtida, may be regarded either as a primordial ancestral form of
this large family, or more probably as the last and most reduced form of
it. In the former case the total absence of coryphal horns and basal feet
is primary, in the latter case secondary, effected by phylogenetic
reduction and loss. But it is also possible that in one part of the
numerous species of this genus the former case, and in another the latter
takes place, and that one part of _Dictyospyris_ may be directly developed
from the Semantida or Coronida (the lattice shell becoming complete),
another part arising from the Tripospyrida or Dipospyrida (the horns and
feet becoming lost).



Subgenus 1. _Dictyospyrantha_, Haeckel.

_Definition._--Basal plate with two large pores only (the primary jugular
pores of _Semantis_).


1. _Dictyospyris distoma_, n. sp. (Pl. 89, figs. 11, 12).

Shell nut-shaped, smooth, or somewhat tuberculate, with deep sagittal
stricture. Pores not numerous, large, roundish-polygonal; three pairs of
large annular pores on each side of the ring. Basal plate with two very
large pentagonal roundish collar pores.

_Dimensions._--Shell 0.06 long, 0.08 broad.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


2. _Dictyospyris stalactites_, n. sp. (Pl. 89, fig. 7).

Shell nut-shaped, covered with irregular ramified tubercles (like
stalactites), with deep sagittal stricture. Pores not numerous, large,
irregular, roundish. Two pairs of large triangular pores on each side of
the ring (the inferior larger). Basal plate with two very large
semicircular collar pores.

_Dimensions._--Shell 0.07 long, 0.09 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms; also fossil
in Barbados.


{1074}3. _Dictyospyris biloba_, n. sp.

Shell subspherical, tuberculate, with slight sagittal stricture. Pores very
numerous, small, circular. No larger pores on either side of the ring.
Basal plate with two very large circular pores, surrounded by a circle of
smaller pores.

_Dimensions._--Shell 0.07 long, 0.08 broad.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.



Subgenus 2. _Dictyospyrella_, Haeckel.

_Definition._--Basal plate with three large collar pores (two paired
posterior cardinal pores and an odd anterior sternal pore).


4. _Dictyospyris triomma_, n. sp.

Shell nut-shaped, smooth, with deep sagittal stricture. Pores not numerous,
large, polygonal roundish, two pairs of very large annular pores on each
side of the ring. Basal plate with three large triangular pores. No free
internal procolumella.

_Dimensions._--Shell 0.06 long, 0.09 broad.

_Habitat._--Indian Ocean, Zanzibar (Pullen), depth 2200 fathoms.


5. _Dictyospyris tristoma_, Ehrenberg.

  _Dictyospyris tristoma_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 70, Taf. xix. fig. 9.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores
numerous, irregular, roundish. Three pairs of larger annular pores on each
side of the ring. Basal plate with three large semi-circular pores (the
sternal odd pore apparently halved by an internal free procolumella).

_Dimensions._--Shell 0.05 long, 0.08 broad.

_Habitat._--Fossil in Barbados and Sicily (Caltanisetta).


6. _Dictyospyris triloba_, Ehrenberg.

  _Dictyospyris triloba_, Ehrenberg, 1876, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 70, Taf. xix. fig. 8.

Shell nut-shaped, spinulate, without external stricture, but with a
complete internal sagittal ring. Pores numerous, subregular circular; no
larger annular pores. Basal plate with three large, heart-shaped two-lobed
collar pores.

_Dimensions._--Shell 0.05 long, 0.07 broad.

_Habitat._--Fossil in Barbados.


{1075}7. _Dictyospyris gigas_, Bütschli.

  _Dictyospyris gigas_, Bütschli, 1880, Zeitschr. f. wiss. Zool., vol.
  xxxvi., p. 539, Taf. xxxii. fig. 14_a_, 14_b_.

Shell subspherical, smooth, with a half (ventral) sagittal stricture, and a
nearly complete internal ring. Pores very numerous and small, circular. No
larger annular pores. Basal plate with three large collar pores (the
sternal odd pore apparently divided into two jugular pores by the visible
free procolumella.) (Compare _Circospyris gigas_, p. 1072 = _Dictyospyris
gigas_, Ehrenberg).

_Dimensions._--Shell 0.1 long, 0.14 broad.

_Habitat._--Fossil in Barbados.



Subgenus 3. _Dictyospyrissa_, Haeckel.

_Definition._--Basal plate with four large collar pores (two larger
posterior cardinal and two smaller anterior jugular pores).


8. _Dictyospyris fenestra_, Ehrenberg.

  Dictyospyris fenestra, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. xix. fig. 11.

Shell nearly cubical, smooth, without external sagittal stricture. Internal
sagittal ring complete. Pores small, roundish; on each side of the ring two
crossed pairs of large, square, equal, annular pores. Basal plate also with
four longer pores of nearly equal size.

_Dimensions._--Shell 0.05 long, 0.07 broad.

_Habitat._--Fossil in Barbados.


9. _Dictyospyris tetrastoma_, Ehrenberg.

  _Dictyospyris tetrastoma_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 70, Taf. xix. fig. 12.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores
numerous, irregular, roundish. No larger annular pores. Basal plate with
four large ovate collar pores (the two cardinal twice as large as the two
jugular pores).

_Dimensions._--Shell 0.05 long, 0.07 broad.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific; also fossil in
Barbados and Sicily.


10. _Dictyospyris spinulosa_, Ehrenberg.

  Dictyospyris spinulosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 70, Taf. xix. fig. 13.

  ? _Ceratospyris borealis_, Bailey, 1856, Amer. Journ. of Science and
  Arts, vol. xxii. pl. i. fig. 3.

Shell nut-shaped, spinulate, without external stricture, with an internal
free sagittal ring. Pores numerous, irregular, roundish; on each side of
the ring two pairs of very large square pores. Basal plate with four large
collar pores.

{1076}_Dimensions._--Shell 0.07 long, 0.08 broad.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750
fathoms; also fossil in Barbados.


11. _Dictyospyris mammillaris_, n. sp. (Pl. 89, figs. 9, 10).

Shell mammillate, nut-shaped, with deep sagittal stricture. Mammillæ of the
surface hemispherical, with a conical apex. Pores not numerous, large,
roundish. Two pairs of large pores on each side of the ring. Basal plate
with four large pores.

_Dimensions._--Shell 0.06 long, 0.08 broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


12. _Dictyospyris anthophora_, n. sp. (Pl. 89, fig. 8).

Shell tuberculate, nut-shaped, nearly cubical, without external sagittal
strictures. Pores not numerous, large, polygonally roundish. Bars between
them compressed, elevated, with large, campanulate or flower-like tubercles
on the nodal points. Basal plate with four large pores.

_Dimensions._--Shell 0.07 long, 0.09 broad.

_Habitat._--North Atlantic, Station 349, depth 2450 fathoms.


13. _Dictyospyris quadriloba_, n. sp.

Shell nut-shaped, smooth, with deep sagittal stricture. Pores numerous,
small, circular, on each side of the ring three to four times as large as
on the lateral sides. Basal plate with four very large collar pores and a
circle of twenty to twenty-five very small peripheral pores.

_Dimensions._--Shell 0.08 long, 0.11 broad.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.


14. _Dictyospyris messanensis_, J. Müller.

  _Dictyospyris messanensis_, J. Müller, 1858, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 46, Taf. ii. fig. 8.

  _Dictyospyris messanensis_, Haeckel, 1862, Monogr. d. Radiol., p. 291.

Shell nut-shaped, spinulate, with deep sagittal stricture. Pores numerous
and small, irregular roundish. No larger annular pores on the sides of the
ring. Basal plate with four large, nearly equal, pear-shaped collar pores.

_Dimensions._--Shell 0.06 long, 0.08 broad.

_Habitat._--Mediterranean; Messina, surface.



Subgenus 4. _Dictyospyromma_, Haeckel.

_Definition._--Basal plate with six or more collar pores.


{1077}15. _Dictyospyris hexastoma_, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores small,
irregular, roundish. Three pairs of larger pores on each side of the ring.
Basal plate with six large pores; the middle pair (cardinal) twice as large
as the anterior (jugular) and the posterior (cervical).

_Dimensions._--Shell 0.08 long, 0.12 broad.

_Habitat._--Fossil in Barbados.


16. _Dictyospyris enneastoma_, n. sp.

Shell ellipsoidal, smooth, without external sagittal stricture, but with an
internal free sagittal ring. Pores small and numerous, regular, circular.
No larger annular pores. Basal plate with nine pores, three larger
interradial alternating with three pairs of adradial.

_Dimensions._--Shell 0.07 long, 0.11 broad.

_Habitat._--South Pacific, Station 297, depth 1775 fathoms.


17. _Dictyospyris polystoma_, n. sp.

Shell nut-shaped, mammillate, with distinct sagittal stricture. Pores small
and numerous, irregular, on each side of the ring three to five times as
large as on the lateral sides. Basal plate with twelve large pores (four
central and four alternate pairs of peripheral).

_Dimensions._--Shell 0.1 long, 0.14 broad.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.



Family LIII. #THOLOSPYRIDA#, n. fam.

(Pl. 87, figs. 7-10; Pl. 89, figs. 1-4; Pl. 95, figs. 14-16).

_Definition._--#Spyroidea# with a galea, but without thorax; the shell
being composed of the bilocular cephalis and of an aboral cupola or galea
arising from its coryphal face.

The family #Tholospyrida# differs from the preceding Zygospyrida, its
ancestral group, in the development of a galea, _i.e._, a fenestrated
hemispherical or dome-shaped cupola, which covers the upper face of the
cephalis like a cap.

Only three species of this family have been hitherto described:
_Pylospyris_ (or _Spyridobotrys_) _trinacria_, figured in my Monograph
(1862), _Pylospyris_ (or _Lithopera_) _denticulata_, figured by Ehrenberg
(1872), and _Lophospyris_ (or _Ceratospyris_) _acuminata_, figured by
Hertwig (1879). Fourteen new species have been found in the collection of
the Challenger, which we dispose here among five genera. These may be
derived from corresponding genera of Zygospyrida by the development of a
galea.

{1078}The number and disposition of the terminal feet around the basal
plate do not vary so much in the Tholospyrida as in the Zygospyrida. We
find here only one genus with three feet, _Tholospyris_ (corresponding to
_Tripospyris_); one genus with two lateral feet, _Lophospyris_
(corresponding to _Dipospyris_); and two genera with numerous feet, the
horned _Sepalospyris_ and the hornless _Tiarospyris_ (the former
corresponding to _Petalospyris_, the latter to _Gorgospyris_). The fifth
genus (_Pylospyris_) has no feet at all, and may be derived from
_Circospyris_ among the Zygospyrida.

The cephalis exhibits in the Tholospyrida the same typical structure which
we have described above of all #Spyroidea# (compare p. 1017). The cupola or
galea, arising from its upper face, seems to be a secondary production,
perhaps caused by an apical growth of the central capsule, or in other
cases by descending branches of the apical horn, which cover the apical
face of the calymma with protecting network.

_Synopsis of the Genera of Tholospyrida._

                              {Three basal feet (two
  I. Subfamily Lophospyrida.  { paired pectoral and
  Two or three basal (cortinar{ an odd caudal),        469. _Tholospyris_.
    feet). Galea with a horn. {
                              {Two paired basal
                              { (pectoral) feet,       470. _Lophospyris_.

  II. Subfamily Tiarospyrida. }Galea with a horn,      471. _Sepalospyris_.
  Numerous basal feet in a    }
   corona (six to nine        }Galea without a horn,   472. _Tiarospyris_.
    or more).                 }

  III. Subfamily Pylospyrida. }Galea with a horn,      473. _Pylospyris_.
  No basal feet.              }



Genus 469. _Tholospyris_,[87] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Tholospyrida# with three basal feet and an apical horn.

The genus _Tholospyris_ is probably the common ancestral form of the
Tholospyrida, and has arisen from _Tripospyris_ by development of a galea
or cupola; this is composed of the apical horn, the lateral branches of
which become connected with lateral spines arising from the coryphal face
of the cephalis, and of lattice-work developed between the former and the
latter. The three descending feet of the basal face are the typical
cortinar feet (one odd caudal and two paired pectoral), the same as in the
old ancestral genera _Cortina_, _Plagoniscus_, _Tripospyris_, &c.



Subgenus 1. _Tholospyrium_, Haeckel.

_Definition._--Basal feet simple, neither forked nor branched.


{1079}1. _Tholospyris tripodiscus_, n. sp. (Pl. 89, fig. 1).

Shell campanulate, smooth, as broad as long, with deep sagittal stricture.
Cephalis compressed, with irregular roundish pores; two or three pairs of
larger annular pores on each side of the ring. Basal plate with four large
pores. Galea with two very large opposite holes (an occipital and a frontal
opening). A slender free perpendicular columella connects the uppermost
part of the sagittal ring with the strong three-sided pyramidal apical
horn. All three feet of equal length, half as long as the ring,
three-sided, prismatic, divergent, with three dentated edges.

_Dimensions._--Shell 0.13 diameter, ring 0.08 long, feet 0.05 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Tholospyris fenestrata_, n. sp. (Pl. 89, fig. 2).

Shell roundish polyhedral, smooth, with slight sagittal stricture. Cephalis
nearly cubical, with irregularly roundish pores; two or three pairs of
larger pores on each side of the ring. Basal plate with two very large
pores. Galea pyramidal, with two large occipital holes. Columella enclosed
in the dorsal wall of the galea, prolonged into an oblique pyramidal spine
of the same length. Two pectoral feet pyramidal, nearly vertical and as
long as the ring, twice as long as the caudal foot.

_Dimensions._--Shell 0.12 diameter, ring 0.07, pectoral feet 0.05 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Tholospyris galeata_, n. sp.

Shell helmet-shaped, thorny, with deep sagittal stricture. Cephalis
campanulate, with subregular circular pores. Basal plate with three large
pores. Galea hemispherical, separated from the cephalis by a sharp
horizontal stricture; pores smaller. A slender free columella connects the
apex of the ring with the strong conical apical horn, which is half as long
as the ring. All three feet of equal length, divergent conical, as long as
the horn.

_Dimensions._--Shell 0.14 diameter, ring 0.09 long, feet 0.08 long.

_Habitat._--Central Pacific, Station 263, depth 2650 fathoms.



Subgenus 2. _Tholospyridium_, Haeckel.

_Definition._--Basal feet forked or branched.


4. _Tholospyris ramosa_, n. sp. (Pl. 89, fig. 3).

Shell helmet-shaped, smooth, with deep sagittal stricture. Cephalis nearly
spherical, with irregularly polygonal pores; four or five pairs of larger
annular pores on each side of the strong angular ring. Cupola flat,
conical, with two pairs of larger pores. Columella enclosed in its dorsal
wall, {1080}bearing an irregularly branched horn. Caudal foot short
conical, simple. Two pectoral feet half as long as the shell, angular,
subvertical, irregularly branched.

_Dimensions._--Shell 0.15 diameter, ring 0.1 long, pectoral feet 0.07 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


5. _Tholospyris cupola_, n. sp. (Pl. 89, fig. 4).

Shell pear-shaped or cupola-shaped, smooth, with slight sagittal stricture.
Cephalis not distinctly separated from the galea, as the ring in the
uppermost part of the shell-wall becomes obliterated. Pores irregularly
polygonal, small and numerous. Basal plate with four large pores. Apical
horn and the three divergent feet, irregularly branched; feet nearly as
long as the shell, about four times as long as the horn.

_Dimensions._--Shell 0.14 diameter, ring 0.1 long, feet 0.12 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



Genus 470. _Lophospyris_,[88] Haeckel, 1881, Prodromus, p. 443 (_sensu
emendato_).

_Definition._--#Tholospyrida# with two lateral basal feet and an apical
horn.

The genus _Lophospyris_ differs from the preceding _Tholospyris_, its
probable ancestral form, in the absence of the caudal foot, and therefore
bears to it the same relation that _Dipospyris_ does to _Tripospyris_. The
two pectoral feet are alone developed and are placed opposite in the
frontal plane. _Lophospyris_ may also be derived from _Dipospyris_ by the
formation of a galea.


1. _Lophospyris dipodiscus_, n. sp. (Pl. 95, fig. 14).

Shell ovate, spinulate, with sharp transverse coronal constriction. Cupola
hemispherical, half as large as the nut-shaped cephalis. Pores irregularly
roundish, much larger on the sagittal constriction. Apical horn pyramidal,
about half as long as the shell. Two lateral feet cylindrical, strongly
curved, about as long as the shell, with some irregular branches; together
forming a nearly complete circle.

_Dimensions._--Shell 0.09 long, 0.08 broad; ring 0.04 long, feet 0.08 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Lophospyris acuminata_, Haeckel.

  _Ceratospyris acuminata_, R. Hertwig, 1879, Organism. d. Radiol., p. 70,
  Taf. vii. fig. 2.

Shell campanulate, smooth, without external transverse stricture. Cupola
conical, half as long and broad as the nut-shaped cephalis. Pores
irregularly roundish, on each side of the sagittal {1081}strictures much
larger. Basal plate with four large triangular pores. Apical horn slender,
prismatic; its outer free part of the same length as the inner columella,
and as the two lateral feet, which are curved, shorter than half the ring.

_Dimensions._--Shell 0.08 long, 0.09 broad; ring 0.06 long; horn and feet
0.03 long.

_Habitat._--Mediterranean, Messina (R. Hertwig).


3. _Lophospyris comosa_, n. sp.

Shell ovate, spiny, with deep transverse stricture. Cupola large,
campanulate, nearly as long and two-thirds as broad as the nut-shaped
cephalis. Pores irregular, roundish, of little different size, Basal plate
with numerous (eight to twelve) similar pores. Apical horn large, nearly as
long as the shell, surrounded by a bunch of smaller divergent spines. Two
lateral feet divergent, larger than the shell, cylindrical; at the distal
end irregularly branched, at the base surrounded by some smaller spines.

_Dimensions._--Shell 0.15 long, 0.11 broad; ring 0.08 long; feet 0.2 long.

_Habitat._--Western Tropical Pacific, Station 206, depth 2100 fathoms.



Genus 471. _Sepalospyris_,[89] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Tholospyrida# with numerous basal feet (eight to twelve or
more). Galea with a horn.

The genus _Sepalospyris_ has been derived from the similar _Petalospyris_
by development of a galea or cupola on the coryphal face of the cephalis,
or from _Tholospyris_ by multiplication of the basal feet. The latter (in
the two observed species from twelve to twenty-five) form a regular corona
around the basal plate.


1. _Sepalospyris platyphylla_, n. sp. Pl. 95, fig. 15.

Shell ovate, rough, with sharp transverse stricture. Cupola with delicate
network, hemispherical, about two-thirds as long and broad as the
nut-shaped thorax. Pores of the latter irregular, roundish; two or three
pairs of large pores on each side of the sagittal stricture. Apical horn
conical, half as long as the shell. Basal coronet with twelve to fifteen
broad, lamellar, truncate, vertical feet, somewhat shorter than the
cephalis.

_Dimensions._--Shell 0.12 long, 0.13 broad; ring 0.06 long; horn 0.04; feet
0.05 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


2. _Sepalospyris polyphylla_, n. sp.

Shell campanulate, rough, with deep transverse stricture. Cupola
hemispherical, about one-third as long and broad as the nut-shaped thorax.
Pores irregular, roundish, a little different in {1082}size. Apical horn
pyramidal, about as long an the shell. Basal coronet with twenty to
twenty-five slender, lamellar, pointed, vertical feet, longer than the
shell.

_Dimensions._--Shell 0.11 long, 0.12 broad; ring 0.07 long; horn 0.1; feet
0.12 to 0.18 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Genus 472. _Tiarospyris_,[90] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Tholospyrida# with numerous basal feet (eight to twelve or
more). Galea without a horn.

The genus _Tiarospyris_ has probably been derived from the preceding
_Sepalospyris_ by reduction and loss of the free apical horn; it therefore
bears to it the same relation that the similar _Gorgospyris_ does to
_Petalospyris_.


1. _Tiarospyris pervia_, n. sp. (Pl. 87, fig. 7).

Shell nut-shaped, smooth, with deep sagittal stricture. Cephalis on the
lateral sides with numerous small roundish pores, on each side of the ring
with a pair of very large holes. Basal plate with two large collar pores.
Cupola flat, cap-shaped, with two large parietal pores above the ring.
Coronet with eight conical, slightly divergent feet, about one-fourth as
long as the shell.

_Dimensions._--Shell 0.08 long, 0.1 broad; ring 0.06 long; feet 0.02 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


2. _Tiarospyris galea_, n. sp.

Shell helmet-shaped, with deep sagittal stricture. Cephalis with irregular,
polygonal pores; on each side of the ring two pairs of larger annular
pores. Basal plate with four large pores. Cupola high, conical, nearly as
long as the cephalis, separated from it by a distinct coronal stricture.
Basal coronet with twelve to sixteen slender curved divergent feet, nearly
as long as the shell.

_Dimensions._--Shell 0.16 long, 0.12 broad; ring 0.1 long; feet 0.15 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


3. _Tiarospyris mitra_, n. sp. (Pl. 87, figs. 9, 10).

Shell subspherical, smooth. Cephalis on the lateral sides with small
roundish, double-contoured pores, on each side of the ring with three to
five pairs of larger pores, each of which is closed by a thin fenestrated
lamella (different on the frontal face, fig. 9, and the dorsal face, fig.
10). Cupola flat, cap-shaped, separated by a distinct coronal stricture,
with similar pores. Basal coronet with, ten to twelve short conical
convergent feet.

_Dimensions._--Shell 0.11 long, 0.12 broad; ring 0.04 long; feet 0.02 long.

_Habitat._--West Tropical Pacific, Station 225, depth 4475 fathoms.


{1083}4. _Tiarospyris amphora_, n. sp. (Pl. 87, fig. 8).

Shell amphora-shaped, in the upper half smooth, in the lower spiny, without
external sagittal stricture. Cephalis subspherical with a small number of
irregular, large, roundish pores, which are closed by a thin fenestrated
lamella. Cupola flat, cap-shaped, with numerous small pores. Base covered
with numerous conical divergent feet of different sizes, the largest
one-third as long as the shell. Internal sagittal ring ovate, nearly free.

_Dimensions._--Shell 0.14 long, 0.13 broad; ring 0.1 long; feet 0.04 long.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.



Genus 473. _Pylospyris_,[91] Haeckel, 1881 Prodromus, p. 443.

_Definition._--#Tholospyrida# without basal feet, with an apical horn.

The genus _Pylospyris_ was first known from a Mediterranean species, called
by me, in 1862, _Spyridobotrys trinacria_. As this name was given
erroneously, on the supposition of a near relation to the Botryodea (=
Polycyrtida), I changed it afterwards to _Pylospyris_. This genus differs
from the other Tholospyrida in the total absence of basal feet, and may
therefore be derived either from them by reduction of the feet, or from
_Dictyospyris_ by formation of a galea.


1. _Pylospyris denticulata_, Haeckel.

  _Lithopera denticulata_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 297, Taf. xii. II. fig. 7.

  _Lithobotrys denticulata_, Ehrenberg, 1844, Monatsber. d. Akad. Berlin,
  p. 203.

Shell spinulate, with slight coronal and deep sagittal constriction, with
irregular, roundish pores of variable size. Galea hemispherical, about half
as long and broad as the nut-shaped cephalis. No symmetrically disposed
larger pores.

_Dimensions._--Galea 0.04 long, 0.06 broad; cephalis 0.08 long, 0.1 broad.

_Habitat._--Antarctic Ocean, Ehrenberg. (Included in the ice.)


2. _Pylospyris trinacria_, Haeckel.

  _Spyridobotrys trinacria_, Haeckel, 1862, Monogr. d. Radiol., p. 341,
  Taf. xii. figs. 8, 9.

Shell tuberculate, with sharp coronal and sagittal stricture. Galea
campanulate, with very small circular pores, and a short conical apical
horn of the same length. Cephalis nut-shaped, with large, irregular,
roundish pores; two pairs of larger annular pores on each side of the
sagittal ring, also four larger pores in the basal plate.

_Dimensions._--Galea 0.03 long, 0.04 broad; cephalis 0.04 long, 0.07 broad.

_Habitat._--Mediterranean, Messina, surface.


{1084}3. _Pylospyris canariensis_, n. sp. (Pl. 95, fig. 16).

Shell rough, with deep coronal and slight sagittal constriction. Galea
hemispherical, with numerous small irregular, roundish pores, about half as
long as the cephalis, with a slender conical horn of twice the length.
Cephalis nut-shaped, with larger roundish pores of very unequal size, three
pairs of larger pores on each side of the ring. Basal plate with two larger
pores.

_Dimensions._--Galea 0.03 long, 0.08 broad; cephalis 0.06 long, 0.11 broad.

_Habitat._--North Atlantic, Canary Islands, surface.



Family LIV. #PHORMOSPYRIDA#, Haeckel (_sensu emendato_) (Pl. 83, figs.
13-15; Pl. 95, figs. 17-19).

  _Phormospyrida_, Haeckel, 1881, Prodromus, p. 442.

_Definition._--#Spyroidea# with a thorax, without galea; the shell composed
of the bilocular cephalis and of a simple thorax arising from its basal
face.

The family #Phormospyrida# differs from the Zygospyrida, their ancestral
group, in the development of a thorax, or a second fenestrated shell-joint,
which arises from the lower face of the cephalis. It corresponds,
therefore, to the Dicyrtida among the #Cyrtoidea#, and may perhaps be,
wholly or partially, the ancestral group of the latter. When the sagittal
ring and the longitudinal constriction of the cephalis disappear, the
Phormospyrida pass over into the Dicyrtida.

Only three species of this family have been hitherto known, which were
found fossil in Barbados, and described by Ehrenberg (1875) as _Lithobotrys
stiligera_ and _Petalospyris confluens_, and by Bütschli (1882) as
_Petalospyris anthocyrtoides_. Fifteen other species are found in the
Challenger collection, which we dispose here among five genera.

Two of these five genera (the horned _Acrospyris_ and the hornless
_Phormospyris_) possess the three typical basal feet of _Cortina_ and
_Tripospyris_, and may be derived from these genera by the development of
network between the bases of the feet. The three other genera possess
numerous feet, and may be derived in the same way from the Polyspyrida; the
apical face differs in the three genera, in _Desmospyris_ it is hornless,
in _Patagospyris_ it bears an apical horn, and in Rhodospyris three horns
(an apical and two lateral or frontal).

The cephalis in the Phormospyrida exhibits the same typical structure,
which we have described above, of all #Spyroidea# (compare, p. 1017). The
thorax or the second joint of the shell arises by reticular connection of
the bases of the basal feet, and represents a cylindrical or
truncate-conical joint in the polypodal forms, or a three-sided joint in
the tripodal forms. The terminal aperture or the mouth of the thorax is
constantly open, and surrounded by the free ends of the feet.

{1085}_Synopsis of the Genera of Phormospyrida._

  I. Subfamily Acrospyrida.     }
                                } One apical horn,     474. _Acrospyris_.
  Three basal cortinar feet     }
   (one odd caudal and two      } No apical horn,      475. _Phormospyris_.
    paired pectoral).           }

  II. Subfamily Rhodospyrida.   { One apical horn,     476. _Patagospyris_.
                                {
  Numerous basal feet in a      { Three apical horns,  477. _Rhodospyris_.
   corona (nine to  twelve or   {
    ore.)                       { No apical horn,      478. _Desmospyris_.



Subfamily 1. ACROSPYRIDA, Haeckel, 1881, Prodromus, p. 441 (_sensu
emendato_).

_Definition._--#Phormospyrida# with three basal feet (an odd caudal and two
paired pectoral).



Genus 474. _Acrospyris_,[92] Haeckel, 1881, Prodromus, p. 441.

_Definition._--#Phormospyrida# with three basal feet and one apical horn.

The genus _Acrospyris_ is probably the oldest and most primitive among the
Phormospyrida, perhaps the original ancestral form of this family. It has
been derived from _Tripospyris_ by the development of lattice-work between
the three basal feet, forming a second joint or thorax. It has also
therefore a close relation to the simplest forms of the triradiate
Dicyrtida: _Dictyophimus_, _Clathrocanium_, &c. It differs from these in
the distinct sagittal constriction of the cephalis, which divides it into
two lateral loculi.


1. _Acrospyris clathrocanium_, n. sp. (Pl. 95, fig. 17).

Shell tuberculate, with distinct collar and deep sagittal stricture.
Cephalis nut-shaped, with numerous irregular, roundish pores; three pairs
of larger annular pores on each side of the ring. Basal plate with four
larger pores (two major cardinal and two minor jugular pores). Apical horn
slender, pyramidal, curved, about as long as the shell, with three recurved
short spines. Thorax three-sided, about twice as large as the cephalis,
with three large basal holes and a broad riband with numerous smaller
holes; three ribs between them stout, pyramidal, strongly curved, prolonged
into three convergent crescentic feet.

_Dimensions._--Cephalis 0.08 long, 0.11 broad; thorax 0.14 long, 0.16
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Acrospyris dictyophimus_, n. sp.

Shell smooth. Cephalis and thorax of nearly the same structure and form as
in the preceding species; it differs from the latter in the shape of the
three stout basal feet, which are {1086}straight, much longer than the
thorax, divergent, and at the broader base irregularly fenestrated, without
three larger holes.

_Dimensions._--Cephalis 0.05 long, 0.08 broad; thorax 0.07 long, 0.12
broad.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


3. _Acrospyris pyramidalis_, n. sp.

Shell three-sided pyramidal, with slight collar stricture. Cephalis
campanulate, with deep sagittal stricture and stout ring, armed with a
strong pyramidal horn of the same length. Thorax shorter and broader,
truncate. Pores irregular, roundish, scarce. Three feet divergent,
three-sided pyramidal, as long as the cephalis.

_Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.02 long, 0.08
broad.

_Habitat._--Fossil in Barbados.


4. _Acrospyris macrocephala_, n. sp.

Shell spinulate, with deep sagittal and very deep collar stricture.
Cephalis very large, nut-shaped, twice as long and broad as the small,
truncate, pyramidal thorax. Pores irregular, roundish. Horn spindle-shaped,
nearly as long as the cephalis; the three divergent feet are of the same
form and size as the horn, and arise as three ribs from the deep collar
stricture.

_Dimensions._--Cephalis 0.1 long, 0.15 broad; thorax 0.05 long, 0.09 broad.

_Habitat._--Fossil in Barbados.


5. _Acrospyris fragilis_, n. sp.

Shell very thin-walled and fragile, with deep sagittal and collar
strictures. Pores very small and numerous, circular. Cephalis nut-shaped,
nearly spherical, with a slender bristle-shaped horn of the same length.
Basal stricture with two large collar pores only (luminella). Thorax nearly
three-sided prismatic, longer than the cephalis, with three parallel ribs,
prolonged into three slender, long, bristle-shaped feet.

_Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.08 long, 0.06
broad.

_Habitat._--North Pacific, Station 244, surface.



Genus 475. _Phormospyris_,[93] Haeckel, 1881, Prodromus, p. 442 (_sensu
emendato_).

_Definition._--#Phormospyrida# with three basal feet, without apical horn.

The genus _Phormospyris_ has been derived from _Acrospyris_, its ancestral
form, by reduction and loss of the apical horn; it therefore bears to the
latter the same relation that _Tristylospyris_ has to the ancestral
_Tripospyris_.


{1087}1. _Phormospyris tricostata_, n. sp. (Pl. 83, fig. 15).

Cephalis nut-shaped, thorny, with deep sagittal and collar strictures, half
as large as the pyramidal thorax. Mouth of the latter dilated and ciliated,
twice as broad as the cephalis. Pores irregular, polygonal, with thin bars.
Three cylindrical, straight, divergent ribs descend in the wall of the
thorax, and are prolonged over the mouth into three short conical teeth.

_Dimensions._--Cephalis 0.06 long, 0.09 broad; thorns 0.08 long, 0.16
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Phormospyris tridentata_, n. sp. (Pl. 95, fig. 18).

Cephalis nut-shaped, with deep sagittal and collar strictures, about twice
as large as the thorax. Mouth of the latter half as broad as the cephalis.
Pores very small and numerous, subregular, circular. Collar plate with four
large triangular pores. In the wall of the thorax three vertical prismatic
ribs descend, which are prolonged over the mouth into three parallel feet
of the same length.

_Dimensions._--Cephalis 0.06 long, 0.08 broad; thorns 0.04 long, 0.06
broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


3. _Phormospyris trifoliata_, n. sp.

Cephalis nut-shaped, with deep sagittal and collar strictures, smaller than
the thorax. Mouth of the latter nearly as broad as the cephalis. Pores
circular, double-contoured, larger in the thorax than in the cephalis. The
thorax has no lateral ribs, but bears around the mouth three large
triangular lamellar terminal feet.

_Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.06 long, 0.05
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Subfamily 2. RHODOSPYRIDA, Haeckel.

_Definition._--#Phormospyrida# with a corona of numerous (nine to twelve or
more) basal feet.



Genus 476. _Patagospyris_,[94] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Phormospyrida# with numerous basal feet (nine to twelve or
more) and an apical horn.

The genus _Patagospyris_ and the two following closely allied genera differ
from the two preceding tripodal genera in the multiplication of the basal
feet, and therefore have to the latter the same relation that the
Polyspyrida (_Petalospyris_) bear to the Tripospyrida (_Tripospyris_). When
the numerous basal feet of _Petalospyris_ become connected by lattice-work,
_Patagospyris_ arises.


{1088}1. _Patagospyris confluens_, Haeckel.

  _Petalospyris confluens_, Ehrenberg, 1885, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. xxii. fig. 5.

Shell tuberculate, with distinct sagittal and collar strictures. Pores
irregular, roundish. Cephalis nut-shaped, larger than the short truncate
thorax. Horn conical, shorter than the cephalis. Peristome with a coronet
of twelve to fifteen short triangular feet, which are parallel and
vertical, slightly curved and shorter than the thorax.

_Dimensions._--Cephalis 0.05 long, 0.07 broad; thorax 0.03 long, 0.07
broad.

_Habitat._--Fossil in Barbadoes.


2. _Patagospyris lanceolata_, n. sp.

Shell tuberculate, with slight sagittal and sharp collar strictures. Pores
subregular, circular. Cephalis subspherical, about as large as the truncate
subcylindrical thorax. Horn spindle-shaped, about as long as the cephalis.
Peristome with a coronet of fifteen to twenty divergent lanceolate lamellar
feet, longer than the thorax.

_Dimensions._--Cephalis 0.08 long, 0.09 broad; thorax 0.07 long, 0.07
broad.

_Habitat._--Fossil in Barbados.


3. _Patagospyris stiligera_, Haeckel.

  _Lithobotrys stiligera_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 76, Taf. iii. fig. 17.

Shell smooth, hyaline, with deep sagittal and collar strictures. Pores very
small and few. Cephalis nut-shaped, bilobed, of the same breadth as the
cylindrical thorax. Horn conical, about as long as the cephalis. Peristome
with a coronet of six to nine broad lamellar feet (in Ehrenberg's figure
broken off).

_Dimensions._--Cephalis 0.04 to 0.05 diameter; thorax 0.06 long, 0.05
broad.

_Habitat._--Fossil in Barbados.


4. _Patagospyris anthocyrtis_, n. sp. (Pl. 95, fig. 19).

Shell smooth, with deep sagittal and deep collar strictures. Pores
irregular, roundish, of various sizes, numerous. Cephalis nut-shaped, with
two inflated bosoms, about twice as broad as the short cylindrical thorax.
Horn stout, pyramidal, about as long as the cephalis. Peristome with a
coronet of fifteen to twenty parallel and vertical triangular lamellar
feet, nearly as long as the thorax.

_Dimensions._--Cephalis 0.05 long, 0.1 broad; thorax 0.04 long, 0.06 broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



Genus 477. _Rhodospyris_,[95] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Phormospyrida# with numerous basal feet (nine to twelve or
more), and with three coryphal horns.

{1089}The genus _Rhodospyris_ differs from the preceding _Patagospyris_ in
the development of three coryphal horns (one odd middle apical horn, and
two paired frontal horns on each of its sides), and therefore bears the
same relation to the latter that the similar _Anthospyris_ does to
_Petalospyris_. When the numerous basal feet of _Anthospyris_ become
connected by lattice-work, _Rhodospyris_ arises.


1. _Rhodospyris tricornis_, n. sp. (Pl. 83, fig. 13).

Cephalis nut-shaped, with deep sagittal stricture, and three short apical
horns of half its length; the middle odd horn is straight, the two paired
lateral horns are curved outwards. Thorax somewhat larger than the
cephalis, dilated around the wide open mouth, with a coronet of twenty-five
to thirty slender basal feet, which are slightly curved and convergent,
about as long as the thorax. Pores small, numerous and circular.

_Dimensions._--Cephalis 0.05 long, 0.07 broad; thorax 0.06 long, 0.08
broad; horns 0.02 long, feet 0.06 long.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.


2. _Rhodospyris triceros_, n. sp.

Cephalis nut-shaped, with deep sagittal and deep collar stricture, and with
three stout divergent horns of nearly equal length. Thorax cylindrical,
twice as long as the cephalis, and of the same breadth, with a coronet of
twelve to sixteen broad, lamellar, rectangular, perpendicular feet around
the mouth, about as long as the cephalis. Pores rather large, subregular,
circular.

_Dimensions._--Cephalis 0.06 long, 0.08 broad; thorax 0.12 long, 0.09
broad.

_Habitat._--Indian Ocean, Singapore (Trebing), surface.



Genus 478. _Desmospyris_,[96] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Phormospyrida# with numerous basal feet (nine to twelve or
more), without a coryphal horn.

The genus _Desmospyris_ differs from the two preceding polypodal genera in
the complete absence of horns on the coryphal face of the cephalis. It
therefore corresponds to _Gorgospyris_ among the Zygocyrtida, and arises
when the numerous basal feet of the latter become connected by
lattice-work.


1. _Desmospyris mammillata_, n. sp. (Pl. 83, fig. 14).

Shell mammillate, with deep sagittal and slight collar constriction.  Pores
irregular, roundish. Cephalis nut-shaped, larger than the inversely conical
thorax, and twice as broad as the constricted {1090}mouth. Coronet of the
peristome with twelve to fifteen short conical convergent feet, shorter
than half the thorax.

_Dimensions._--Cephalis 0.06 long, 0.09 broad; thorax 0.04 long, 0.06
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Desmospyris cyrtocolpos_, n. sp.

Shell smooth, with deep sagittal and collar strictures. Pores subregular,
circular, double-contoured, very small and numerous. Cephalis nut-shaped,
larger than the short truncate thorax. Coronet with eighteen to twenty-four
slender, irregular, pointed, convergent feet, about twice as long as the
thorax.

_Dimensions._--Cephalis 0.08 long, 0.12 broad; thorax 0.04 long, 0.1 broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


3. _Desmospyris anthocyrtoides_, Haeckel.

  _Petalospyris anthocyrtoides_, Bütschli, 1882, Zeitschr. f. wiss. Zool.,
  vol. xxxvi. pp. 533, 539, Taf. xxxii. fig. 19, _a-c_.

Shell tuberculate, with slight sagittal and sharp collar strictures. Pores
subregular, circular. Cephalis nut-shaped, larger than the short truncate
thorax. Coronet with fifteen to twenty short conical, parallel and vertical
feet, about as long as the thorax.

_Dimensions._--Cephalis 0.06 long, 0.09 broad; thorax 0.02 long, 0.07
broad.

_Habitat._--Fossil in Barbados.


4. _Desmospyris carpocanium_, n. sp.

Shell smooth, with slight sagittal and slight collar strictures. Pores
subregular, circular, small and numerous. Cephalis campanulate, smaller
than the ovate thorax. Coronet with fifteen to twenty irregular lamellar
feet, which are longer than the thorax, pointed, nearly vertical and
parallel.

_Dimensions._--Cephalis 0.05 long, 0.08 broad; thorax 0.07 long, 0.1 broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.



Family LV. #ANDROSPYRIDA#, n. fam. (Pl. 88-90).

_Definition._--#Spyroidea# with galea and thorax; the shell composed of a
bilocular cephalis and of two secondary joints, a galea arising from its
upper face, and a thorax arising from its lower face.

{1091}The family #Androspyrida# differs from the three preceding families
of #Spyroidea# in the three-jointed shell, in which the galea of the
Tholospyrida and the thorax of the Phormospyrida are combined; it may
therefore be derived from the latter by development of a galea, or from the
former by formation of a thorax. The common ancestral group of these three
families is probably the Zygospyrida. But it may be that a part of the
Androspyrida has originated directly from the #Stephoidea#.

Two species only of this family were hitherto known, _Amphispyris
reticulata_ (figured, in 1872, by Ehrenberg, as _Dictyospyris_) and
_Sphærospyris sphæra_ (described, in 1882, by Bütschli, as _Dictyospyris_).
Thirty new species were found in the collection of the Challenger, and are
here disposed in seven genera. But perhaps these may represent three
different families, which we here enumerate as subfamilies; the
Lamprospyrida, Perispyrida, and Nephrospyrida.

The Lamprospyrida, the first subfamily, are tripodal #Spyroidea# with galea
and thorax; they may therefore be regarded as a combination of
_Tholospyris_ and _Acrospyris_. In the simpler form, _Androspyris_ (Pl. 83,
fig. 8), the network of the shell is simple, and allows a very clear
recognition of the internal structure. In the splendid _Lamprospyris_,
derived from it (Pl. 89, figs. 13, 14) the delicate network is more or less
spongy. The large apical horn is branched and fenestrated in the latter and
simple in the former.

The Perispyrida, the second subfamily, possess no free apophyses, but a
three-jointed shell with two distinct transverse strictures, an upper
mitral and a lower collar stricture. The network of this shell is
incomplete in _Amphispyris_ (Pl. 88, figs. 2-7), being developed only in
the frontal or lateral perimeter, thus making it probable that this
subfamily may have arisen directly from the Tympanida (_Toxarium_, Pl. 88,
fig. 1; Pl. 93, figs. 18-20). The network of _Tricolospyris_ (Pl. 88, figs.
8-11) is complete, of another shape in the cephalis than in the galea and
thorax; it is doubled or spongy in _Perispyris_ (Pl. 88, figs. 12, 13).

The Nephrospyrida, the third subfamily, contains two very different genera
only, each of which may represent a separate family. _Sphærospyris_ (Pl.
83, fig. 4) possesses a spherical or subspherical lattice-shell, the
central part of which includes a sagittal ring, connected with the inner
face of the sphere by a number of paired apophyses, corresponding to those
of _Lithocircus_; it may be easily confounded with some #Sphæroidea#
(_Carposphæra_), but the enclosed ring leaves no doubt as to its true
origin. _Nephrospyris_ (Pl. 90) has a flat discoidal shell of considerable
size, usually kidney-shaped or cordate, with a deep sagittal incision at
the base, indicating the region where the pseudopodia are protruded from
the porochora. The violin-shaped central capsule has two large lateral
lobes on each side of the including sagittal ring, and the transverse
nucleus is perpendicular to its sagittal plane (Pl. 90, figs. 7, 10).
_Sphærocircus_ as well as _Nephrospyris_ have probably arisen independently
from the Stephanida.

{1092}_Synopsis of the Genera of Androspyrida._

  -------------------------------------------------------------------------
  I. Subfamily Lamprospyrida. Three free basal feet.
  -------------------------------------------------------------------------
  Lattice-work simple, not  {Apical horn usually
   spongy.                  { simple, not
                            { fenestrated,            479. _Androspyris_.

  Lattice-work wholly or    {Apical horn usually
   partly spongy.           { branched and
                            { fenestrated,            480. _Lamprospyris_.
  -------------------------------------------------------------------------
  II. Subfamily Perispyrida. No free basal feet. Shell three-jointed.
  -------------------------------------------------------------------------
                            {Lattice-work only
                            { complete in the
                            { frontal ring,           481. _Amphispyris_.
  Shell with two transverse {
   coronal strictures (one  {Lattice-work complete
   superior mitral and one  { on all sides,           482. _Tricolospyris_.
   inferior collar          {
   stricture).              {Lattice-work double
                            { or spongy,              483. _Perispyris_.

  -------------------------------------------------------------------------
  III. Subfamily Nephrospyrida.
       No free basal feet. Shell spherical or discoidal.
  -------------------------------------------------------------------------
                            {Shell spherical or
                            { subspherical,           484. _Sphærospyris_.
  Shell without external    {
   transverse stricture.    {Shell discoidal,
                            { kidney-shaped or
                            { subcircular,            485. _Nephrospyris_.



Subfamily 1. LAMPROSPYRIDA, Haeckel.

_Definition._--#Androspyrida# with three free basal feet (an odd posterior
caudal foot and two paired anterior pectoral feet).



Genus 479. _Androspyris_,[97] n. gen.

_Definition._--#Androspyrida# with three free basal feet and a simple
apical horn; lattice-work of the three-jointed shell simple, not spongy.

The genus _Androspyris_ is probably the most original form of the
Androspyrida, and represents, together with the following _Lamprospyris_,
the subfamily of Lamprospyrida, which always possess three free basal feet,
an odd posterior or caudal foot, and two paired anterior or pectoral feet.
It may be derived either from _Acrospyris_ by development of a cupola, or
from _Tholospyris_ by development of a thorax; the common ancestral form of
these three typical genera is, no doubt, _Tripospyris_. Some species of
_Androspyris_ reach a considerable size and are distinguished by a peculiar
external form resembling somewhat a human figure.


1. _Androspyris homunculus_, n. sp.

Shell thorny, with two deep transverse constrictions and irregular
polygonal pores. Galea subspherical, with a strong pyramidal oblique horn,
about two-thirds as large as the cephalis, which has the form of a human
thorax, includes a strong ovate sagittal ring, and bears on each side a
stronger lateral spine. Thorax short and broad, prolonged into three
latticed divergent feet; the {1093}two lateral (pectoral) feet are like the
legs of a human body, and are twice as long as the cephalis and as the
tail-like caudal feet. (The whole shell exhibits a curious similarity to a
human figure, more than in the following nearly allied species.)

_Dimensions._--Length of the shell (including horn and feet) 0.4, breadth
0.1 to 0.15.

_Habitat._--Central Pacific, Station 273, depth 2350 fathoms.


2. _Androspyris anthropiscus_, n. sp. (Pl. 83, fig. 8).

Shell rough, with two distinct transverse constrictions and irregular
polygonal pores. Galea ovate, with a slender conical oblique horn, about as
large as the cephalis, which exhibits a deep longitudinal furrow in the
sagittal dorsal line. Thorax half as long, prolonged into three short
latticed feet; the terminal spines of the two lateral feet are vertical and
parallel, that of the caudal foot larger, directed obliquely backwards.

_Dimensions._--Length of the shell (including horn and feet) 0.35, breadth
0.1 to 0.12.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Androspyris pithecus_, n. sp. (Pl. 95, fig. 20).

Shell smooth, with two slight transverse constrictions. Galea conical, with
a short conical horn, longer than the nut-shaped cephalis. Thorax with
three nearly vertical and parallel feet of equal length. Pores in the galea
and thorax very small and numerous, circular, in the cephalis much larger,
irregular, roundish.

_Dimensions._--Length of the shell (including horns and feet) 0.25, breadth
0.06 to 0.08.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


4. _Androspyris aptenodytes_, n. sp.

Shell smooth, with two slight transverse constrictions and irregular,
roundish pores. Galea hemispherical, with a short conical horn, about as
large as the roundish cephalis and half as large as the ovate thorax. The
three feet arise immediately beyond the collar stricture, are equal,
divergent, curved, about as long as the cephalis, and are not terminal (as
in the three preceding species), but lateral appendages of the thorax.

_Dimensions._--Length of the shell 0.2, breadth 0.05 to 0.07.

_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.



Genus 480. _Lamprospyris_,[98] Haeckel, 1881, Prodromus, p. 447.

_Definition._--#Androspyrida# with three free basal feet and a fenestrated
apical horn; lattice-work of the three-jointed shell wholly or partly
spongy.

The genus _Lamprospyris_ differs from the preceding _Androspyris_, its
ancestral form, mainly in the higher development of the lattice-work of the
large shell. Whilst this in {1094}the latter genus is a simple
lattice-plate, it here becomes more or less spongy, and sometimes forms a
very dense and delicate wickerwork. The apical horn and the three basal
feet are commonly also fenestrated. The two annular strictures, which
separate the cephalis from the conical cupola and the inflated thorax, are
commonly not so distinct as in the preceding genus. Some species belong to
the largest Spyroidea and reach more than half a millimetre in length.


1. _Lamprospyris darwinii_, n. sp. (Pl. 89, fig. 13).

Shell nearly pear-shaped, with two distinct annular strictures, and uneven
papillate surface. The total length is equal to twice the greatest breadth,
and to seven times the length of the ring. Apical horn free, irregularly
branched and fenestrated, as long as the included columella beyond it. The
three diverging feet are strongly curved, S-shaped, and completely included
by loose lattice-work. In the middle of their length they give off a simple
strong lateral branch. The loose arachnoidal lattice-work is rather equally
developed.

_Dimensions._--Length of the entire shell (including the apophyses) 0.5,
greatest breadth 0.25, ring 0.07 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Lamprospyris lyellii_, n. sp.

Shell slender, pear-shaped, very similar to the preceding species, but
differing in the following characters--the branched horn is much larger and
twice as long as the columella; the two annular transverse strictures
(separating the three joints) are deeper. The free internal branches of the
three included feet are forked. Lattice-work looser than in the preceding
species.

_Dimensions._--Length of the entire shell 0.6, breadth 0.2, ring 0.09 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Lamprospyris huxleyi_, n. sp. (Pl. 89, fig. 14).

Shell ovate, spiny, with two slight annular transverse strictures; their
length equal to one and a half times the breadth, and up to seven times the
length of the ring. Apical horn quite included by the loose lattice-work of
the large conical cupola, which is as long as the cephalis and thorax
together. The three slender feet are also included in the lattice-work and
only one-third as long as the shell, nearly vertical. Lattice-work much
denser than in the two preceding species.

_Dimensions._--Length of the shell 0.4, breadth 0.26, ring 0.06 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


4. _Lamprospyris hookeri_, n. sp.

Shell ovato-conical, very similar to the preceding species, but smooth, not
spiny. The apical horn and the three feet are much longer, not included in
the network, but freely prominent, half {1095}as long as the shell and
nearly vertical, parallel. The arachnoidal lattice-work is much denser in
the middle third (cephalis) than in the upper third (cupola) of the lower
third (thorax).

_Dimensions._--Length of the shell (without appendages) 0.45, breadth 0.3,
ring 0.08 long.

_Habitat._--Central Pacific, Station 270, depth 2925 fathoms.


5. _Lamprospyris spenceri_, n. sp.

Shell slender, ovate, very similar to the preceding species; differing from
it in the larger cupola, which is as long as the cephalis and thorax
together. The three feet are much shorter and weaker, more divergent. This
differs from all four preceding species in the possession of a large double
apical horn; the two horns are strong, pyramidal, straight, strongly
divergent, and as long as the cupola.

_Dimensions._--Length of the shell (without the appendages) 0.3, breadth
0.2, ring 0.05 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Subfamily 2. PERISPYRIDA, Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Androspyrida# without free basal feet, with three distinct
joints separated by two parallel transverse strictures.



Genus 481. _Amphispyris_,[99] Haeckel, 1881, Prodromus, p. 444.

_Definition._--#Androspyrida# without free basal feet, with three distinct
joints, separated by two transverse strictures; lattice-work of the shell
only complete in the frontal ring, with large open holes on the ventral and
dorsal face.

The genus _Amphispyris_ and the two following genera arising from it,
represent together the peculiar small subfamily of Perispyrida. This may
have originated directly from _Toxarium_ (family Tympanida, Pl. 88, fig. 1;
Pl. 93, figs. 18-20), the large holes between its arches and rings becoming
filled up by lattice-work; in _Amphispyris_ this intercalated network
remains incomplete on the ventral and dorsal faces, whilst in
_Tricolospyris_ it becomes complete, and in _Perispyris_ spongy.



Subgenus 1. _Amphispyrium_, Haeckel.

_Definition._--On each side of the ring-plane three pairs of large annular
meshes; no middle zygomatic ring is developed between the two tympanic
transverse rings (superior orbital and inferior maxillary ring).


{1096}1. _Amphispyris thorax_, n. sp. (Pl. 88, fig. 4).

Shell thorax-shaped, as long as broad, with a deep sternal incision and two
slight transverse strictures. On each side of the ring-plane three pairs of
large, irregular, annular holes of nearly equal size, the middle holes
nearly half as broad as the shell. No zygomatic bars between the orbital
and maxillary bars. Lateral lattice-girdle narrow, with few small roundish
meshes.

_Dimensions._--Shell 0.17 long, 0.17 broad, ring 0.06 long.

_Habitat._--Central Pacific, Station 270, depth 2925 fathoms.


2. _Amphispyris quadrigemina_, n. sp. (Pl. 88, fig. 6).

Shell shaped like the "corpora quadrigemina cerebralia," with two deep
crossed strictures, a coronal transverse stricture and a sagittal sternal
stricture. On each side of the ring plane three pairs of large, irregular,
annular, double holes, the middle holes larger than the upper and lower
holes, and about one-fourth as long as the shell. No zygomatic bars between
the orbital and maxillary bars. Lateral lattice-girdle broad, with numerous
small meshes.

_Dimensions._--Shell 0.13 long, 0.16 broad, ring 0.07 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Amphispyris reticulata_, Haeckel.

  _Dictyospyris reticulata_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 289, Taf. x. fig. 19.

Shell thorax-shaped, one and one-fifth times as long as broad, with a deep
sternal incision and two distinct transverse strictures. On each side of
the ring-plane three pairs of large annular holes of nearly equal size,
about one-third as long as the shell. No zygomatic bars between the orbital
and maxillary bars. Lateral girdle narrow, with few large polygonal meshes.

_Dimensions._--Shell 0.18 long, 0.15 broad.

_Habitat._--Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).



Subgenus 2. _Amphispyridium_, Haeckel.

_Definition._--On each side of the ring-plane four pairs of larger annular
meshes; a middle horizontal zygomatic ring is developed between the two
tympanic transverse rings (superior orbital and inferior maxillary ring).


4. _Amphispyris sternalis_, n. sp. (Pl. 88, fig. 2).

Shell thorax-shaped, one and one-fifth times as long as broad, with deep
sternal incision and two distinct transverse (tympanic) strictures. On each
side of the ring-plane four pairs of large irregular, annular holes; the
fourth (inferior or buccal) pair is the longest. The middle of the sagittal
ring {1097}is crossed by horizontal zygomatic bars (between the ascending
orbital and the descending maxillary bars). Lateral lattice-girdle narrow,
with few large meshes.

_Dimensions._--Shell 0.24 long, 0.2 broad; ring 0.09 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


5. _Amphispyris subquadrata_, n. sp. (Pl. 88, fig. 5).

Shell compressed, nearly square, spiny, with slight sternal incision and
two distinct transverse strictures. Similar to the preceding species; four
pairs of irregular annular pores of nearly equal size. Zygomatic ring
complete. Lateral lattice-girdle narrow, with few large meshes.

_Dimensions._--Shell 0.14 long, 0.12 broad; ring 0.06 long.

_Habitat._--Central Pacific, Station 285, depth 2275 fathoms.


6. _Amphispyris costata_, n. sp. (Pl. 88, fig. 3).

Shell compressed, nearly square, with slight sternal incision and two
obliterated transverse strictures. Similar to the two preceding species;
with four pairs of large annular pores, the two middle of which (the
orbital and nasal holes) are much larger than the superior (frontal) and
inferior (oral) holes. Zygomatic ring incomplete. Lateral lattice-girdle
broad, with very numerous, small, irregular, polygonal pores.

_Dimensions._--Shell 0.2 long, 0.16 broad; ring 0.07 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


7. _Amphispyris toxarium_, n. sp. (Pl. 88, fig. 7).

Shell inflated, with deep sternal incision and two distinct transverse
strictures. Similar to the preceding species, but with deeper constriction
and looser lattice-work. Four pairs of large, irregular, annular pores, the
central two of which are much larger. Zygomatic ring complete. Lateral
girdle broad, with irregular pores of very different size.

_Dimensions._--Shell 0.2 long, 0.14 broad; ring 0.09 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 482. _Tricolospyris_,[100] Haeckel, 1881, Prodromus, p. 443.

_Definition._--#Androspyrida# without free basal feet, with three distinct
joints, separated by two transverse strictures; lattice-work of the shell
complete, simple.

The genus _Tricolospyris_ has arisen from the preceding _Amphispyris_, its
ancestral form, by development of lattice-work which completely closes the
large open holes remaining on the ventral and dorsal faces of the latter.


{1098}1. _Tricolospyris kantiana_, n. sp. (Pl. 88, fig. 10).

Shell smooth, one and a half times as long as broad, with two deep
transverse strictures. Pores of the cephalis large, roundish, of nearly
equal size. Cupola and thorax hemispherical, of about the same size and
form, with numerous and small, double-contoured, roundish pores.

_Dimensions._--Shell 0.12 long, 0.08 broad; ring 0.04 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Tricolospyris leibnitziana_, n. sp. (Pl. 88, fig. 9).

Shell spiny, twice as long as broad, with two deep transverse strictures.
Pores of the cephalis large, roundish, polygonally framed, of very
different size; two middle transverse rows of smaller pores enclosed
between a superior and an inferior row of very large pores. Cupola and
thorax hemispherical, about equal, with much smaller and very numerous
roundish pores.

_Dimensions._--Shell 0.15 long, 0.07 broad; ring 0.06 long.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.


3. _Tricolospyris baconiana_, n. sp. (Pl. 88, fig. 8).

Shell rough, twice as long as broad, with two sharp strictures. Pores of
the cephalis large, very irregular, partly lobated. Cupola hemispherical,
smaller than the campanulate thorax, both with smaller irregular pores.

_Dimensions._--Shell 0.15 long, 0.08 broad; ring 0.06 long.

_Habitat._--Western Tropical Pacific, Station 215, depth 2500 fathoms.


4. _Tricolospyris newtoniana_, n. sp. (Pl. 88, fig. 11).

Shell spiny, slender, three times as long as broad, with two distinct
strictures. Pores of the cephalis very large, irregular. Cupola
hemispherical, only one-third as long as the slender inversely conical
abdomen, both with irregular, much smaller pores.

_Dimensions._--Shell 0.22 long, 0.08 broad; ring 0.05 long.

_Habitat._--Western Tropical Pacific, Station 206, depth 2100 fathoms.



Genus 483. _Perispyris_,[101] Haeckel, 1881, Prodromus, p. 444.

_Definition._--#Androspyrida# without free basal feet, with three distinct
joints, separated by two transverse strictures; lattice-work of the shell
double or spongy.

The genus _Perispyris_ differs from the preceding _Tricolospyris_, its
ancestral form, in the development of a secondary outer shell, which
encloses the inner primary one either like an enveloping cortical shell or
like a spongy veil. This is produced by the concrescence of meeting
branches, which arise from spines of the inner shell.


{1099}1. _Perispyris bicincta_, n. sp. (Pl. 88, fig. 13).

Shell smooth, with two deep transverse annular strictures and a deep
sagittal incision at the sternal base; one and a half times as long as
broad. Cephalis nut-shaped, with large irregular roundish pores and very
broad bars. Everywhere from its surface there arise numerous slender
arborescent radial beams; by the anastomoses of their ramified branches
there arise the flat cap-shaped cupola and the larger bilobed thorax; and
also the external enveloping shell with loose delicate network.

_Dimensions._--Inner shell 0.17 long, 0.1 broad; outer shell 0.23 long,
0.17 broad; ring 0.06 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Perispyris spongiosa_, n. sp.

Shell rough, with two distinct transverse strictures and a deep sternal
incision, similar to the preceding; the radial beams arising from the inner
shell, and forming by anastomosing branches the outer shell, are thinner
and more numerous, and the framework of the latter on the surface is very
dense and spongy, therefore the shell is dark and not transparent.

_Dimensions._--Inner shell 0.18 long, 0.12 broad; outer shell 0.24 long,
0.18 broad; ring 0.08 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


3. _Perispyris lentellipsis_, n. sp. (Pl. 88, fig. 12).

Shell smooth, lentelliptical, with three different isopolar axes,
perpendicular one to another. Transverse and sagittal strictures are
wanting; but the large enclosed ring and the two pairs of large adjacent
annular meshes indicate clearly the position and size of the hidden
cephalis. The two other joints (the cupola on the upper and the thorax on
the lower pole of the cephalis) are nearly equal, cap-shaped or
hemispherical. The outer lentelliptical shell is little larger than the
inner, connected with it by numerous thin bristle-shaped radial beams, and
exhibits a delicate arachnoidal lattice-work.

_Dimensions._--Inner shell 0.15 long, 0.1 broad; outer shell 0.18 long,
0.13 broad; ring 0.08 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Subfamily 3. NEPHROSPYRIDA (vel PARADICTYIDA, Haeckel, 1881).

_Definition._--#Androspyrida# without free basal feet and external
constrictions. Shell either spherical or discoidal.



Genus 484. _Sphærospyris_,[102] n. gen.

_Definition._--#Androspyrida# with a spherical or subspherical shell,
without basal incision and transverse constriction; without free basal
feet.

{1100}The genus _Sphærospyris_ differs from all other #Spyroidea# in the
regular spherical or spheroidal form of the lattice-shell. It may therefore
be easily confounded with some species of the #Sphæroidea#; but the
internal sagittal ring, placed in the median plane of the fenestrated
sphere and connected with it by radial beams, leaves no doubt that it is
derived from a true Spyroid, either _Dictyospyris_ or _Amphispyris_, or
another genus. Sometimes also four larger collar pores are visible.


1. _Sphærospyris sphæra_, Haeckel.

  _Dictyospyris sphæra_, Bütschli, 1882, Zeitschr. f. wiss. Zool. vol.
  xxxvi. pp. 511, 539, Taf. xxxii. fig. 15, _a_, _b._

Shell smooth, nearly spherical, slightly flattened at the base, with small
regular circular pores. In the centre of the basal plate a regular
rectangular cross with four equal collar pores.

_Dimensions._--Diameter of the shell 0.11, of the enclosed ring 0.06.

_Habitat._--Fossil in Barbados.


2. _Sphærospyris quadriforis_, n. sp.

Shell rough, nearly spherical, slightly flattened at the base, with small
regular circular pores. In the centre of the basal plate a bilateral
symmetrical cross with four ovate collar pores; two cardinal pores twice as
large as the two jugular pores and six to eight times as broad as the other
shell-pores.

_Dimensions._--Diameter of the shell 0.26, of the enclosed ring 0.09.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


3. _Sphærospyris globosa_, n. sp. (Pl. 83, fig. 4).

Shell smooth, perfectly spherical, with small subregular circular pores. In
the centre of the basal plate no larger collar pores. (The original collar
pores are here of the same size as the other pores, and cannot therefore be
distinguished.)

_Dimensions._--Diameter of the shell 0.13, of the enclosed ring 0.06.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



Genus 485. _Nephrospyris_,[103] Haeckel, 1881, Prodromus, p. 444.

_Definition._--#Androspyrida# with a discoidal, kidney-shaped, or
subcircular shell, with a basal incision; without transverse constriction
and free basal feet.

The genus _Nephrospyris_ is one of the most peculiar and most modified of
the #Spyroidea#, of extraordinary size, in this respect surpassing all
other genera of this {1101}suborder, and differing from them in its flat
discoidal form. The diameter of the compressed shell often reaches one half
millimetre or more; its perimeter is elliptical or nearly circular, smooth,
constantly with a characteristic deep sternal incision or a basal sinus on
the basal pole of the main axis. The central sagittal ring is comparatively
small. The margin is often inflated like a delicate reticular girdle, and
contains a large number of peculiar spherical or roundish nucleated cells
(Pl. 90, figs. 6-10). According to the observations of Dr. John Murray,
made on living _Nephrospyris_, they are Vorticellina, perhaps constant
Symbiontes.



Subgenus 1. _Nephrodictyum_, Haeckel, 1881, Prodromus, p. 444.

_Definition._--Network of the shell simple, with bars of nearly equal
breadth.


1. _Nephrospyris renilla_, n. sp. (Pl. 90, figs. 9, 10).

Shell kidney-shaped, one and a half times as broad as long, and three times
as long as the deep kidney-shaped sternal incision. Ring with six pairs of
branched apophyses, the bars of the apical pair vertical, of the basal pair
divergent. The corresponding bars of the two middle pairs (on the frontal
and the occipital face) form together on each side a large pentagonal or
hexagonal naso-orbital area, which is surrounded by four or five large
polygonal meshes; the other meshes become smaller towards the inflated
margin. All meshes simple, without arachnoidal framework.

_Dimensions._--Shell 0.3 to 0.4 long, 0.4 to 0.5 broad; ring 0.08 to 0.1
long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Nephrospyris nephridium_, n. sp.

Shell kidney-shaped, one and two-third times as broad as long, very similar
to the preceding species (or only a variety of it?). Ring with seven pairs
of branched apophyses. The large naso-orbital area is on the dorsal or
occipital side simple, on the ventral or facial side divided by an
equatorial pair of transverse horizontal branches into two superior
orbital, and two inferior nasal holes. Sternal incision ovate. All meshes
simple.

_Dimensions._--Shell 0.25 to 0.35 long, 0.4 to 0.5 broad; ring .007 to 0.08
long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


3. _Nephrospyris phaseolus_, n. sp.

Shell kidney-shaped, twice as broad as long, very similar to the two
preceding species (or only a variety of them?). Ring with eight pairs of
branched apophyses. The large naso-orbital area (between the mitral and
collar ring) is on the dorsal and on the ventral side divided by two
equatorial pairs of horizontal branches into two superior (orbital and
occipital), and two inferior (nasal and suboccipital) holes. Sternal
incision cordate. All meshes simple.

_Dimensions._--Shell 0.25 long, 0.5 broad; ring 0.06 to 0.07 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


{1102}4. _Nephrospyris cordata_, n. sp.

Shell heart-shaped, about as long as broad. Ring with six pairs of branched
apophyses (as in _Nephrospyris renilla_, Pl. 90, fig. 9). No equatorial
transverse branches. Sternal incision cordate, deeper than in all other
species of the genus, nearly half as long as the shell. All meshes of the
network simple.

_Dimensions._--Shell 0.32 long, 0.36 broad; ring 0.05 to 0.06 long.

_Habitat._--Central Pacific, Station 263, depth 2650 fathoms.



Subgenus 2. _Paradictyum_, Haeckel, 1881, Prodromus, p. 444.

_Definition._--Network of the shell double; the larger meshes separated by
strong bars, and filled up by a very delicate secondary arachnoidal
network.


5. _Nephrospyris paradictyum_, n. sp. (Pl. 90, figs. 1-8).

  _Paradictyum paradoxum_, Haeckel, 1881, Prodromus et Atlas, _loc. cit._

Shell nearly circular, ten times as broad as the inflated marginal girdle,
and three times as long as the sternal incision. Ring with six pairs of
branched apophyses; the bars of the apical pair nearly vertical, of the
basal pair divergent; the corresponding and opposite bars of the two middle
pairs (on the occipital and on the frontal face) form together a large
middle naso-orbital area; above and below this lie six pairs of larger
meshes. All larger meshes of the network are filled up by very delicate
arachnoidal framework. The inflated and delicately reticulated marginal
girdle of this and of the following closely allied species is usually
filled up by nucleated roundish cells (fig. 7), which are Vorticellinæ,
according to the observations of Dr. John Murray on living specimens.

_Dimensions._--Diameter of the shell 0.5 to 0.6, of the marginal girdle
0.05 to 0.07; ring 0.07 to 0.09 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


6. _Nephrospyris paradoxa_, n. sp.

Shell kidney-shaped, one and one-third times as broad as long, six times as
broad as the inflated marginal girdle, and half as long as the sternal
incision. Ring with six pairs of apophyses. Above and below the large
naso-orbital holes lie ten pairs of larger meshes. All the meshes are
filled up by very delicate arachnoidal network.

_Dimensions._--Length of the shell 0.4 to 0.5, breadth 0.5 to 0.7; ring
0.06 to 0.08 long.

_Habitat._--Central Pacific, Station 270, depth 2925 fathoms.


{1103}----


Suborder II. Botryodea, Haeckel, 1881 (Pl. 96).

  _Polycyrtida_, Haeckel, 1862, Monogr. d. Radiol., p. 341.
  _Polycyrtida_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p.
      519.
  _Botryodea_ (= _Botrida_ vel _Botryida_), Haeckel, 1881, Prodromus, p.
      439.

_Definition._--NASSELLARIA with a complete lattice-shell, exhibiting
constantly a lobate and multilocular cephalis, with three to five or more
separated lobes, and two to three or more constrictions.


The suborder #Botryodea# differs from the other #Cyrtellaria# in the
multilocular and lobate shape of the cephalis, which is composed of at
least three or four, often five or six, and sometimes even a greater number
of lobes, which are separated by constrictions and partly also by internal
septa. This characteristic shape is found neither in the #Spyroidea# (with
bilocular cephalis) nor in the #Cyrtoidea# (with simple cephalis). The
affinities of the former group to the two latter form a very complicated
problem, which is not yet solved; the morphology of the #Botryodea# is the
most difficult part in the system of NASSELLARIA, and what we can here
give, are incomplete and unsatisfactory beginnings only.

Up to the year 1860 only a single genus of the #Botryodea# was known,
_Lithobotrys_, one of the oldest genera of "_Polycystina_," and described
by Ehrenberg in 1844 (Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p.
74). He gave the following definition:--"Loricæ siliceæ articuli in adulto
non in seriem, sed in uvæ brevis formam, id est in loculos plus minus
discretos nonnullos contiguos dispositi. Proxime ad Lithocampem accedit."
In his first System (1847) _Lithobotrys_ is placed with _Lithocampe_ among
his family Lithochytrina. Afterwards (1860) Ehrenberg added two new genera,
under the names _Botryocampe_ and _Botryocyrtis_ and figured some species
of these incompletely in his last works (1872, 1875).

In my Monograph I founded for these three genera the separate subfamily of
Polycyrtida, added as a fourth genus _Spyridobotrys_, and gave to the group
the following definition (1862, loc. cit., p. 341):--"Lattice-shell divided
by two or more annular strictures, partly longitudinally, partly
transversely, into three or more unequal chambers, which are placed in
different planes and have a different relation to the poles of the
shell-axis."

The new and remarkable forms of #Botryodea#, which I subsequently found in
the Challenger collection, demonstrated that the #Botryodea# differ from
the other #Cyrtellaria# (the #Cyrtoidea# as well as the #Spyroidea#) in a
far higher degree than I formerly had supposed. A synopsis of the figures
in Pl. 96 will give sufficient evidence of this view. Therefore in my
Prodromus (1881, p. 439) {1104}I completely separated the #Botryodea# (or
Botrida) from the other suborders of #Cyrtellaria# (Spyrida and Cyrtida).

Bütschli gave, in 1882, in his paper on the Cyrtida (_loc. cit._) a very
accurate description of _Lithobotrys geminata_, and pointed out its close
affinity to _Lithocorythium_ and _Lithomelissa_, and the importance of an
oblique septum separating the cephalis into a smaller anterior and a larger
posterior lobe. His views on the #Botryodea# (as a subordinate group of the
#Cyrtoidea#) are however incomplete, since the peculiar forms, described in
the following pages, were unknown to him.

According to the wide morphological divergence of the different
#Botryodea#, and the numerous peculiar forms developed from it, we here
divide the whole group into three families and ten genera, with fifty-five
species. These form, however, only a small part of the large and varied
mass of closely related forms which are found in the rich collections of
the Challenger. The great difficulty of researches on their intimate
structure, and the great amount of time required for it, prevented me from
giving a more complete and exact description than the one here given. The
observation of the small shells from all the different sides is a difficult
task, requiring years of work, and its satisfactory explanation would be
possible only by means of numerous figures.

The three families of #Botryodea#, here described, correspond to the three
first groups of #Cyrtoidea#. The first family, Cannobotryida, corresponds
to the Monocyrtida clausa and to the Zygospyrida; their shell consists of a
cephalis only, without subsequent joints. The second family, Lithobotryida,
corresponds to the Dicyrtida and Phormospyrida; their shell is composed of
a cephalis and a thorax, both joints being separated by a transverse
cortinar septum and a collar stricture. The third family, Pylobotryida, has
a three-jointed shell, like the Tricyrtida, with cephalis, thorax and
abdomen.

The cephalis is the most characteristic part of the shell of the
#Botryodea# and its lobulate and multilocular shape separates them from the
#Spyroidea# and #Cyrtoidea#. It represents the whole shell in the
Cannobotryida, and in the young state of the two other families, which
afterwards develop a thorax (Lithobotryida) and an abdomen (Pylobotryida).
The typical lobulation of the cephalis is probably originally caused by
internal septa; and these may be originated by branches of the internal
columella, which corresponds either to the central ascending columella of
the #Plectoidea# or to the excentric ascending dorsal rod of the sagittal
ring of the #Stephoidea#. But afterwards, when the original septa disappear
and are lost by reduction, only the external constrictions remain to
indicate the limits of the single lobes.

Among the internal septa and the corresponding external constrictions which
effect the lobulation of the cephalis, may be distinguished primary or
constant septa and secondary or inconstant septa.  As primary septa we
regard firstly an oblique frontal {1105}septum and secondly a vertical
sagittal septum. The frontal septum (described accurately by Bütschli) has
usually two or three pairs of pores and ascends obliquely from the base to
the anterior face of the cephalis, where it is inserted in the orbital
region; it divides the cephalis into a smaller anterior or facial lobe and
a larger posterior or occipital lobe. The latter is commonly higher and
more developed than the former and partly covers its upper face, like the
crest of a helmet. The facial lobe is again bisected by an incomplete
sagittal septum and a corresponding partial constriction on the anterior
face. We find, therefore, in this original cephalis of the #Botryodea#,
three primary lobes, an odd larger occipital lobe and two paired smaller
facial lobes. The typical trilobed cephalis may be regarded perhaps as the
common original form of the #Botryodea#.

The secondary and inconstant constrictions which we find in many
#Botryodea#, and which produce a greater number of lobes in the cephalis,
require further accurate observation. The following cases of lobation may
be considered as the most important:--(1) Cephalis with four lobes,
opposite in two pairs (two larger occipital and two smaller facial lobes,
separated by a complete sagittal and an oblique frontal constriction); (2)
cephalis with four unequal lobes, two of which are odd and sagittal, two
paired and lateral (the odd occipital lobe usually larger and the odd
mandibular lobe smaller than the two paired lateral or buccal lobes); (3)
cephalis with five lobes (a large odd occipital lobe and two pairs of
smaller lobes, anterior nasal, and lateral buccal lobes); (4) cephalis with
five lobes, three of which are odd (a posterior occipital, middle frontal,
and anterior facial lobe), and one pair of lateral lobes; (5) cephalis with
six lobes, opposite in pairs (two larger occipital, two smaller nasal and
two intermediate lateral or buccal lobes); (6) cephalis with six lobes, two
of which are odd and sagittal (a large occipital and a smaller nasal lobe),
four opposite in pairs (two anterior and two posterior buccal lobes); (7)
cephalis with seven lobes, three of which are odd (a large posterior
occipital, a middle frontal, and an anterior small nasal lobe), four
opposite in two pairs (an anterior buccal and a posterior temporal pair);
(8) cephalis with eight lobes, two of which are odd (a large posterior
occipital and a small anterior frontal lobe) and six opposite in three
lateral pairs; (9) cephalis with nine lobes, three of which are odd (an
occipital, a frontal and a nasal lobe) and six opposite in three lateral
pairs; (10) cephalis with ten lobes, two of which are odd (a large
occipital and a smaller frontal lobe) and the other eight opposite in
pairs; (11) cephalis with numerous lobes (twelve to fifteen or more) which
are symmetrically disposed on each side of the median plane; (12) cephalis
with numerous lobes (twelve to fifteen or more) which are irregularly and
sometimes spirally conglomerated.

All these different forms of lobation require a far more thorough
examination than I can devote to them, and may furnish examples of regular
laws of development. The irregular forms are rather common, and I have
found some very irregular #Botryodea# {1106}(not here described) in which I
could not determine the topographical regions of the cephalis. The
difficulty in the examination of these complicated forms is increased by
their very small size, which does not reach the usual dimensions of the
other #Cyrtellaria#. In some cases I was able to observe on the base of the
cephalis the same typical cortinar pores (in two or three pairs), which we
also find in the same part of the cephalis in the #Spyroidea# and
#Cyrtoidea#, and which are inherited from the Semantida.

The thorax of the #Botryodea#, or the second shell-joint, absent in the
Cannobotryida, is usually of very simple form, ovate, truncate, conical or
cylindrical, and consists of a secondary joint, developed from the base of
the cephalis. The thorax is usually small, about the same size as the
cephalis or a little larger, whilst in the #Cyrtoidea# it is commonly much
larger than the latter. Its terminal mouth is closed by a lattice-plate in
the Botryocellida, while it remains open in the Botryopylida and
Pylobotryida.

The abdomen, or the third shell-joint, developed in the Pylobotryida only,
generally also exhibits a very simple shape, like the thorax, and it is a
tertiary joint developed from the base of the thorax. It exhibits to the
latter the same relation as in the Tricyrtida. The terminal mouth of the
abdomen remains open in the Botryocyrtida; it becomes closed by a
lattice-plate in the Botryocampida.

The lattice-plate forming the shell of the #Botryodea# is usually very thin
and fragile, with very small circular pores. These are often very numerous,
at other times scarce, and sometimes nearly wanting, so that the shell
appears hyaline. In this group there never occurs that great variety in
form and size of the pores, which numerous #Cyrtoidea# and #Spyroidea#
exhibit.

The radial apophyses which are found in the majority of #Botryodea# seem to
correspond in position and relation to the typical radial beams of the
other NASSELLARIA, viz., three descending basal feet arising from the base
of the cephalis, and an ascending vertical apical horn arising from the top
of the cephalis. Here also they seem to be inherited from the #Plectoidea#
or #Stephoidea# (_Cortina_, _Cortiniscus_). But whilst these four typical
radial beams in the other NASSELLARIA are usually simple spines or solid
rods, here they usually appear as hollow cylindrical tubes, the thin wall
of which is pierced by the same small pores as the shell. These porous
tubes are either straight or slightly curved, often inflated and ovate at
the base. We find in their number and disposition the same variety as in
the simple radial spines of the other NASSELLARIA. The original number may
here also be seen in the development of four typical beams, an ascending
apical tube on the top of the cephalis, and three descending basal tubes on
its base; the odd posterior tube of the latter corresponds to the caudal
foot, the two paired anterior to the pectoral feet. There is often also a
fourth foot developed opposite to the caudal, and representing a sternal
tube. Sometimes also two superior tubes are developed, a posterior
occipital and an anterior frontal. The different {1107}apophyses may be
lost by reduction. I have never observed #Botryodea# with more than five
apophyses.

_The Central Capsule_ of the #Botryodea# is not yet sufficiently known, no
living species having been observed. In some preparations from specimens in
the Challenger collections, stained by Dr. John Murray with carmine
immediately after the dredging operation, single #Botryodea# are to be
found in which the central capsule is deeply coloured. In _Botryopera
quinqueloba_ (Pl. 96, fig. 2) it filled up the greater part of the cephalis
and seemed to be divided into some small lobes. In _Lithobotrys
sphærothorax_ (Pl. 96, fig. 15) it was divided into four lobes, three of
which filled the trilobed cephalis, the fourth large lobe occupying a great
part of the spherical thorax. Details of their structure, unfortunately,
were not recognisable. There can, however, be no doubt that they are the
same as in all other NASSELLARIA.

_Synopsis of the Families of_ #Botryodea#.

  1. Shell monothalamous, consisting of the lobate
     cephalis only,                                       1. CANNOBOTRYIDA.

  2. Shell dithalamous, composed of a lobate cephalis
     and a simple thorax,                                 2. LITHOBOTRYIDA.

  3. Shell trithalamous, composed of a lobate cephalis,
     a thorax and an abdomen,                             3. PYLOBOTRYIDA.



Family LVI. #CANNOBOTRYIDA#, Haeckel (_sensu emendato_).

  _Cannobotryida_, Haeckel, 1881, Prodromus, p. 440.

_Definition._--Botryodea monothalamia, the shell of which represents a
lobate cephalis, without thorax and abdomen.

The family #Cannobotryida# (retained here with a stricter definition than
originally was given in my Prodromus) comprises those #Botryodea#, in which
the whole shell is represented by the cephalis alone, without thorax and
abdomen. Since the two latter joints, found in the two following families,
are secondary productions, the Cannobotryida must be regarded as the
ancestral forms of all #Botryodea#, in an ontogenetic as well as in a
phylogenetic sense.

Two species only of this family have been hitherto known, incompletely
described by Ehrenberg as _Lithobotrys triloba_ and _Lithobotrys
quadriloba_. A great number of similar forms are to be found in the
Radiolarian ooze of the Central Pacific, but they are very minute, and
difficult to examine. We can describe here only twelve species of these,
which we arrange in two genera; _Botryopera_ without porous tubes, and
_Cannobotrys_ bearing a variable number of porous cylindrical tubes (one to
five). The number of lobes of the cephalis is also variable in each genus
(one to five or more). If in the future these minute and interesting shells
should be better examined, it would {1108}be advisable to distinguish a
number of genera according to the different number of the porous tubes and
of the lobes of the cephalis. The base of the latter is constantly closed
by a basal lattice-plate, and usually exhibits two or three pairs of
cortinar pores, identical with those of the Semantida.

The phylogenetic origin of the Cannobotryida may be found either in the
Zygospyrida or in the Monocyrtida; they differ from these two similar
groups in the lobation of the cephalis, which is effected by the
development of internal septa and external constrictions.

_Synopsis of the Genera of Cannobotryida._

  Cephalis without porous tubes,                    486. _Botryopera_.

  Cephalis with a variable number of porous tubes,  487. _Cannobotrys_.



Genus 486. _Botryopera_,[104] n. gen.

_Definition._--#Cannobotryida# without tubes on the cephalis.

The genus _Botryopera_ is the simplest form among the #Botryodea#, the
shell consisting of a lobate cephalis only, without tubes or radial
appendages. It may be derived either from _Dictyospyris_ or from
_Archicapsa_ by development of the horizontal fold in the frontal face of
the shell, and the corresponding internal frontal septum, which separates
the larger occipital lobe from the smaller facial half; the latter may be
divided again into paired frontal lobes, lateral buccal lobes, &c.
_Botryopera_ may be the common ancestral form of many #Botryodea#.


1. _Botryopera cyrtoloba_, n. sp. (Pl. 96, fig. 1).

Cephalis trilobate; the posterior odd occipital lobe helmet-shaped, about
twice as large as the two paired anterior frontal lobes, which are subovate
and covered by the upper half of the former. Pores small and numerous,
subregular, circular; some larger pores at the base.

_Dimensions._--Length of the shell 0.08, basal breadth 0.06.

_Habitat._--Central Pacific, Station 265 to 274, depth 2350 to 2925
fathoms.


2. _Botryopera triloba_, Haeckel.

  _Lithobotrys triloba_, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 30.

Cephalis trilobate; the occipital lobe subcylindrical, one and a half times
as long as the two frontal lobes, which are slender, ovate and not covered
by the former. Pores small and numerous.

_Dimensions._--Length of the shell 0.05, breadth 0.03.

_Habitat._--Fossil in Tertiary rocks of the Mediterranean (Sicily, Greece,
&c.)


{1109}3. _Botryopera quadriloba_, Haeckel.

  _Lithobotrys quadriloba_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad.
  d. Wiss. Berlin, p. 84.

Cephalis quadrilobate; the occipital lobe helmet-shaped, one and a half
times as long as the two paired hemispherical buccal lobes, and twice as
large as the anterior frontal lobe. Pores not numerous, rather large,
circular.

_Dimensions._--Length of the shell 0.06, breadth 0.04.

_Habitat._--Fossil in Barbados and North America (Virginia).


4. _Botryopera quinqueloba_, n. sp. (Pl. 96, fig. 2).

Cephalis quinquelobate; the occipital lobe helmet-shaped, and twice as long
as the two hemispherical frontal lobes, three times as long as the
subspherical lateral buccal lobes. Pores scarce, small, circular.

_Dimensions._--Length of the shell 0.07, basal breadth 0.05.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.


5. _Botryopera multiloba_, n. sp.

Cephalis multilobate; the posterior odd occipital lobe ovate, and of about
the same size as the anterior frontal half of the shell, which is clustered
and divided into five to seven smaller lobes, an odd subspherical sternal
lobe, and on each side of it two or three pairs of smaller subspherical
lobes.

_Dimensions._--Length of the shell 0.09, breadth 0.06.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



Genus 487. _Cannobotrys_,[105] Haeckel, 1881, Prodromus p. 440.

_Definition._--#Cannobotryida# with tubes on the cephalis.

The genus _Cannobotrys_ differs from the preceding _Botryopera_ in the
development of hollow radial tubes, arising from the lobate cephalis in
various numbers. According to their number the genus may be divided into
various subgenera: (1) _Cannobotrantha_ (_monocanna_) with a single apical
tube; (2) _Cannobotrella_ (_dicanna_) with two divergent tubes, an
ascending apical and a descending sternal one; (3) _Cannobotrissa_
(_tricanna_) with three tubes in the sagittal plane (an upper apical, a
posterior caudal, and an anterior sternal); (4) _Cannobotromma_
(_tetracanna_) with four radial tubes disposed like the four typical spines
of _Cortina_ (compare p. 950), and _Cannobotrusa_ (_pentacanna_) with five
radial tubes disposed like the five typical spines of _Stephanium_ (p.
952). {1110}Perhaps these five groups may be separated as five genera,
possessing near relations to five very different genera of NASSELLARIA
(_Circospyris_, _Halicapsa_, _Archibursa_, _Cortina_, _Stephanium_, &c.)


1. _Cannobotrys monocanna_, n. sp.

Cephalis trilobate, with a single cylindrical straight apical tube on the
apex of the occipital lobe, which is helmet-shaped, and about one and a
half times as long as the two subspherical frontal lobes. Pores small and
numerous, subregular, circular.

_Dimensions._--Length of the shell 0.05, breadth 0.03.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


2. _Cannobotrys dicanna_, n. sp.

Cephalis quadrilobate, with two divergent tubes, an odd apical tube on the
apex of the posterior occipital lobe, and an odd sternal tube on the
anterior frontal lobe. Between these two odd lobes lie two paired lateral
or buccal lobes, of about the same size. Shell nearly hyaline, with very
few minute pores.

_Dimensions._--Length of the shell 0.06, breadth 0.04.

_Habitat._--Indian Ocean; Madagascar (Rabbe), surface.


3. _Cannobotrys tricanna_, n. sp. (Pl. 96, fig. 3).

Cephalis quinquelobate, with three curved cylindrical tubes in the sagittal
plane; an ascending apical tube on the apex of the helmet-shaped occipital
lobe, and two horizontal tubes on the base of the shell (a posterior
caudal, _c_, and an anterior sternal, _z_). The two frontal lobes are
hemispherical, and twice as large as the two lateral buccal lobes. Pores
very small and numerous.

_Dimensions._--Length of the shell 0.08, basal breadth 0.06.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


4. _Cannobotrys sagittalis_, n. sp.

Cephalis multilobate, with three straight divergent cylindrical tubes in
the sagittal plane; a vertical apical tube on the apex of the ovate
occipital lobe, and two horizontal tubes on the base, as in the preceding
similar species; it differs from the latter in the greater number of lobes
(seven or nine), the two frontal lobes being divided into two or four
secondary lobules.

_Dimensions._--Length of the shell 0.1, breadth 0.07.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


5. _Cannobotrys cortina_, n. sp. (Pl. 96, fig. 4).

Cephalis quinquelobate, with four cylindrical nearly straight tubes of
equal size; an ascending, nearly vertical, apical tube on the apex of the
occipital lobe, and three divergent descending tubes {1111}on the base of
the shell (an odd posterior caudal tube and two paired anterior pectoral
tubes). The two lateral buccal lobes are twice as large as the two anterior
frontal lobes, and half as large as the posterior odd occipital lobe. The
four tubes in this and the following species correspond probably to the
four spines of _Cortina_ (p. 950).

_Dimensions._--Length of the shell 0.07, basal breadth 0.06.

_Habitat._--Central Pacific, Stations 263 to 274, depth 2350 to 2925
fathoms.


6. _Cannobotrys tetracanna_, n. sp.

Cephalis multilobate, with four cylindrical curved tubes conical at their
wider base, corresponding to those of the preceding species and to the four
spines of _Cortina_. The odd occipital lobe is of about the same size as
the anterior part of the shell, which is cleft into three pairs of roundish
lobes, one pair of anterior larger frontal lobes, and two pairs of smaller
lateral buccal lobes. Pores very few and minute.

_Dimensions._--Length of the shell 0.11, basal breadth 0.07.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.


7. _Cannobotrys pentacanna_, n. sp.

Cephalis quinquelobate, with five cylindrical slender curved tubes, three
of which are placed in the sagittal plane (a superior apical, a posterior
caudal, and an anterior sternal), whilst the other two are paired and
diverge laterally (two pectoral tubes). The five tubes correspond exactly
to the five typical spines of _Stephanium_ (p. 952). The helmet-shaped
occipital lobe of the shell is twice as large as each of the two anterior
frontal lobes, and three times as large as each of the two lateral buccal
lobes. Pores numerous.

_Dimensions._--Length of the shell 0.07, basal breadth 0.04.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



Family LVII. #LITHOBOTRYIDA#, n. fam.

_Definition._--Botryodea dithalamia, the shell of which is composed of a
lobate cephalis and a simple thorax, without abdomen.

The family #Lithobotryida# comprises those #Botryodea# in which the shell
is divided by a transverse annular constriction into a lobate cephalis and
a simple thorax. They correspond therefore to the Dicyrtida among the
#Cyrtoidea#, and to the Phormospyrida among the #Spyroidea#. The thorax, or
the second shell-joint, is in all these three families a secondary
production, arising from the base of the cephalis; therefore the
Lithobotryida must be phylogenetically derived from the Cannobotryida.

Several species of _Lithobotrys_ were first described by Ehrenberg as
_Lithobotrys_ and _Lithocorythium_. These two genera are, however,
identical, as has been {1112}demonstrated by Bütschli (1882, _loc. cit._,
p. 519). Some other species united by Ehrenberg with _Lithobotrys_ belong
to other genera. The number of Lithobotryida found in the "Radiolarian
ooze" of the Challenger collection, is far greater than that of the
Cannobotryida and Pylobotryida. But only a small part of them could be
thoroughly examined and described here, so that their number may be greatly
augmented by further accurate researches. We here arrange those forms in
four genera, representing two different subfamilies. The terminal mouth of
the thorax remains open in the Botryopylida, whilst it becomes closed by a
lattice-plate in the Botryocellida. In each group there are shells with and
without porous tubes. The number of these tubes, and also the number of
lobes of the cephalis, is very variable, and may in future serve for the
distinction of more genera.

_Synopsis of the Genera of Lithobotryida._

                               {Cephalis without porous
  I. Subfamily Botryopylida.   { tubes,                 488. _Botryopyle_.
                               {
  Mouth of the thorax open.    {Cephalis with a
                               { variable number of
                               { porous tubes,          489. _Acrobotrys_.

                               {Cephalis without
  II. Subfamily Botryocellida. { porous tubes,          490. _Botryocella_.
                               {
  Mouth of the thorax closed   {Cephalis with a
    by a lattice-plate.        { variable number of
                               { porous tubes,          491. _Lithobotrys_.



Genus 488. _Botryopyle_, Haeckel, 1881, Prodromus, p. 440.

_Definition._--#Lithobotryida# without tubes on the cephalis, and with the
mouth of the thorax open.

The genus _Botryopyle_ comprises the simplest forms of Lithobotryida, the
lobate cephalis bearing no tubes and the basal mouth of the thorax
remaining open. It may be derived either from _Dictyocephalus_ or from
_Desmospyris_, by development of lobes on the cephalis and of an internal
frontal septum, separating the larger occipital lobe from the smaller
frontal half of the shell. The latter may be divided again into anterior
frontal lobes, lateral buccal lobes, &c.


1. _Botryopyle sethocorys_, n. sp. (Pl. 96, fig. 7).

Cephalis trilobate, separated by a deep collar constriction from the
hemispherical thorax, which is twice as broad. Occipital lobe
helmet-shaped, little longer than the two hemispherical frontal lobes.
Surface spiny. Pores irregular, roundish, of very different size.

_Dimensions._--Length of the shell 0.1, breadth 0.07.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


{1113}2. _Botryopyle cribrosa_, Haeckel.

  _Lithobotrys cribrosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 76, Taf. iii. fig. 20.

  ? _Lithobotrys biceps_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 295, Taf. ix. fig. 23.

Cephalis trilobate, separated by a slight collar constriction from the
ovate thorax, which is somewhat smaller. Occipital lobe very large,
helmet-shaped, longer than the thorax and twice as long as the two
subspherical frontal lobes. Pores regular, circular, scarce.

_Dimensions._--Length of the shell 0.11, breadth 0.05.

_Habitat._--Fossil in Barbados.


3. _Botryopyle cephalodes_, Haeckel.

  _Lithocorythium cephalodes_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 78, Taf. iv. fig. 6.

Cephalis quinquelobate, separated by a slight collar constriction from the
larger conical thorax, which is gradually dilated towards the wide mouth.
Occipital lobe helmet-shaped, little longer than the frontal half of the
cephalis, which is divided into two pairs of lateral chambers,
corresponding to the four crossed pores of the sagittal septum, figured by
Ehrenberg. The figure of the latter is inverse, seen from the frontal face,
a part of the frontal wall having been broken off.

_Dimensions._--Length of the shell 0.08, breadth 0.05.

_Habitat._--Fossil in Barbados.


4. _Botryopyle dictyocephalus_, n. sp. (Pl. 96, fig. 6).

Cephalis multilobate, separated by an oblique constriction from the
subcylindrical thorax, which is somewhat larger and slightly curved.
Occipital lobe conical, of the same length as the posterior part of the
triangular frontal half of the shell, which is divided into five to seven
lobes, two or three odd lobes in the median part, and one or two pairs of
lateral lobes; very variable in size and form of the lobes. Mouth of the
thorax wide, truncate.

_Dimensions._--Length of the shell 0.12, breadth 0.07.

_Habitat._--Central Pacific, Station 271 to 274, depth 2350 to 2750
fathoms.


5. _Botryopyle inclusa_, n. sp. (Pl. 96, fig. 5).

Cephalis multilobate, campanulate, separated by a sharp constriction from
the inflated thorax, which is nearly twice as long and broad. Both joints
of the shell are irregularly lobate, with numerous vaulted lobes of
different sizes, and partly internal septa. Pores small and numerous.

_Dimensions._--Length of the shell 0.1, breadth 0.06.

_Habitat._--Mediterranean (Candia), Spratt, depth 1620 fathoms.



{1114}Genus 489. _Acrobotrys_, Haeckel,[106] 1881, Prodromus, p. 440.

_Definition._--#Lithobotryida# with tubes on the cephalis, and with the
mouth of the thorax open.

The genus _Acrobotrys_ differs from the preceding _Botryopyle_ in the
development of radial tubes, and from its probable ancestral form,
_Cannobotrys_, in the development of a thorax, the basal mouth of which
remains open. According to the varying number of the tubes we may
distinguish the following five subgenera (corresponding to those of
_Cannobotrys_), viz., (1) _Acrobotrantha_ (_monosolenia_) with a single
(apical) tube; (2) _Acrobotrella_ (_disolenia_) with two divergent tubes
(an apical and a sternal); (3) _Acrobotrissa_ (_trisolenia_) with three
sagittal tubes (an apical, a caudal, and a sternal); (4) _Acrobotromma_
(_tetrasolenia_) with four tubes, like the four typical spines of
_Cortina_; and (5) _Acrobotrusa_ (_pentasolenia_) with five feet,
corresponding to the five typical spines of _Stephanium_.


1. _Acrobotrys monosolenia_, n. sp.

Cephalis trilobate, with a single straight apical tube, which ascends
vertically from the apex of the occipital lobe, and is pointed at the
distal end, with an anterior oblique aperture. Two frontal lobes paired,
ovate, half as long as the helmet-shaped occipital lobe. Thorax ovate,
twice as long as the cephalis. Pores very scarce.

_Dimensions._--Length of the shell 0.08, breadth 0.06.

_Habitat._--Mediterranean (Corfu), surface.


2. _Acrobotrys disolenia_, n. sp. (Pl. 96, fig. 10).

Cephalis trilobate, with three odd ovate lobes of nearly equal size in the
sagittal plane and two divergent straight slender cylindrical tubes, a
vertical apical tube on the occipital lobe, and a horizontal nasal tube on
the frontal lobe; the middle lobe between them is somewhat smaller. Thorax
ovate, about twice as large as the cephalis, with constricted mouth. Pores
small and numerous.

_Dimensions._--Length of the shell 0.1, breadth 0.06.

_Habitat._--Central Pacific, Station 265 to 274, depth 2350 to 2925
fathoms.


3. _Acrobotrys aquaria_, n. sp.

Cephalis quinquelobate, with two divergent long cylindrical curved tubes.
Occipital lobe helmet-shaped, with an ascending apical tube; nasal lobe
conical, with a descending sternal tube; {1115}between them a smaller odd
middle lobe, and on each side of the latter an ovate frontal lobe. Thorax
inflate, twice as long and broad as the cephalis. Pores small, scarce.

_Dimensions._--Length of the shell 0.09, breadth 0.07.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.


4. _Acrobotrys acuminata_, n. sp. (Pl. 96, fig. 9).

Cephalis sexlobate, with two divergent tubes. Occipital and frontal lobes
ovate, odd; between them a cupola-shaped apical lobe, bearing an ascending
pointed apical tube. On each side at the base a small buccal lobe, and
between the paired buccal lobes an anterior nasal lobe with a descending
curved sternal tube. Thorax smaller than the cephalis. Pores numerous and
small.

_Dimensions._--Length of the shell 0.11, breadth 0.09.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


5. _Acrobotrys auriculata_, n. sp. (Pl. 96, fig. 11).

Cephalis quadrilobate, with three pointed and auriculate tubes, two
ascending apical (an anterior and a posterior) in the helmet-shaped
occipital lobe, and a descending sternal tube on the base of the frontal
lobe; between the lobes two lateral paired buccal lobes. Thorax
campanulate, twice as broad as the cephalis.  Pores rather large and
numerous.

_Dimensions._--Length of the shell 0.1, breadth 0.08.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


6. _Acrobotrys trisolenia_, n. sp. (Pl. 96, fig. 8).

Cephalis quadrilobate, with four odd lobes and three divergent curved
tubes, an ascending apical tube in the conical occipital lobe, and two
descending tubes on the anterior and posterior basal lobes; between these
three lobes a small central lobe. Thorax ovate, about as large as the
cephalis. Pores small and numerous.

_Dimensions._--Length of the shell 0.11, breadth 0.05.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


7. _Acrobotrys tetrasolenia_, n. sp.

Cephalis trilobate, with four slender cylindrical tubes. Occipital lobe
helmet-shaped, with an apical tube on the apex and a caudal tube on the
base. Two frontal lobes ovate, prolonged into two paired pectoral tubes.
The four tubes correspond in position to the four spines of Cortina. Thorax
inflate, ovate, larger than the cephalis. Pores very scarce, rather large,
irregular.

_Dimensions._--Length of the shell 0.08, breadth 0.05.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


8. _Acrobotrys pentasolenia_, n. sp.

Cephalis quinquelobate, with five short conical tubes; three divergent odd
tubes arise from three odd lobes; an apical from the occipital lobe, a
posterior caudal from the suboccipital lobe, and an {1116}anterior sternal
from the nasal lobe. Two paired lateral tubes arise from the base of two
ovate frontal lobes. The five tubes correspond in disposition to the five
spines of Stephanium. Thorax truncate. Pores small.

_Dimensions._--Length of the shell 0.12, breadth 0.09.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



Genus 490. _Botryocella_,[107] Haeckel, 1881, Prodromus, p. 440.

_Definition._--#Lithobotryida# without tubes on the cephalis, and with the
mouth of the thorax closed.

The genus _Botryocella_ differs from the closely allied _Botryopyle_ in
having the mouth of the thorax closed, and may be derived from it by
development of a lattice-plate, effecting this closure. It bears therefore
the same relation to the latter that _Dicolocapsa_ has to _Dictyocephalus_.


1. _Botryocella nucula_, Haeckel.

  _Lithobotrys nucula_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 76, Taf. iii. fig. 16.

  _Lithobotrys adspersa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 76, Taf. iii. fig. 15.

Cephalis trilobate; occipital lobe helmet-shaped, nearly twice as long as
the two ovate frontal lobes. Thorax about as long as the cephalis. Pores
very small and scarce.

_Dimensions._--Length of the shell 0.06, breadth 0.03.

_Habitat._--Fossil in Barbados.


2. _Botryocella borealis_, Haeckel.

  _Lithobotrys borealis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 294, Taf. ii. fig. 3.

Cephalis trilobate; occipital lobe ovate, little longer than the two ovate
frontal lobes. Thorax about twice as long as the cephalis. Pores very
numerous and small.

_Dimensions._--Length of the shell 0.08, breadth 0.04.

_Habitat._--North Atlantic, Greenland, depth 1000 to 2000 fathoms.


3. _Botryocella tricellaris_, n. sp.

Cephalis trilobate, with three odd sagittal lobes; the middle or central
lobe larger than the anterior frontal and smaller than the posterior
occipital lobe. Thorax nearly spherical, about as long as the cephalis.
Pores small and scarce.

_Dimensions._--Length of the shell 0.08, breadth 0.06.

_Habitat._--North Atlantic, Station 353, depth 2965 fathoms.


{1117}4. _Botryocella quadricellaris_, n. sp. (Pl. 96, fig. 13).

Cephalis quadrilobate; the helmet-shaped occipital lobe twice as long as
the two paired subspherical buccal lobes, and three times as long as the
odd spherical frontal lobe. Thorax nearly spherical, about as long as the
cephalis.

_Dimensions._--Length of the shell 0.1, breadth 0.05.

_Habitat._--Central Pacific, Station 272, depth 4475 fathoms.


5. _Botryocella quadrigemina_, n. sp. (Pl. 96, fig. 14).

Cephalis quadrilobate, with two pairs of lateral ovate lobes and complete
sagittal constriction; the two occipital lobes nearly twice as large as the
two frontal lobes. Thorax ovate, separated from the cephalis by a collar
septum with four cortinar pores (fig. 14).

_Dimensions._--Length of the shell 0.09, breadth 0.06.

_Habitat._--Indian Ocean, Sunda Strait (Rabbe), surface.


6. _Botryocella multicellaris_, n. sp. (Pl. 96, fig. 12).

Cephalis multilobate; occipital lobe helmet-shaped, very large, about twice
as long and broad as the frontal half of the shell, which is divided into
six to eight small roundish clustered lobes. Thorax subspherical, of about
the same size as the cephalis.

_Dimensions._--Length of the shell 0.1, breadth 0.05.

_Habitat._--South Pacific Station 297, depth 1775 fathoms.



Genus 491. _Lithobotrys_,[108] Ehrenberg, 1844, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 74.

_Definition._--#Lithobotryida# with tubes on the cephalis, and with the
mouth of the thorax closed.

The genus _Lithobotrys_, the oldest and first known of the #Botryodea#, was
founded by Ehrenberg in 1844, and was one of his five oldest genera of
Polycystina. It represented by itself the suborder #Botryodea# until the
year 1860. The numerous species described by Ehrenberg belong to very
different genera of #Botryodea#, and partly also of #Spyroidea#. Following
Bütschli (1882) we retain here the name _Lithobotrys_ for those species,
the type of which is _Lithobotrys geminata_. The genus _Lithocorythium_ of
Ehrenberg is for the greater part identical with it. When in the preceding
genus _Acrobotrys_ the mouth of the thorax becomes closed by lattice work,
_Lithobotrys_ arises. In the latter as well as in the former the number of
tubes on the cephalis is different, and may characterise different
subgenera.


{1118}1. _Lithobotrys geminata_, Ehrenberg.

  _Lithobotrys geminata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 76, Taf. iii. fig. 19.

  _Lithobotrys geminata_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi, p. 519, Taf. xxxiii. fig. 27, a to c.

  ? _Lithocorythium platylophus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 78, Taf. iv. fig. 5.

Cephalis trilobate, with a single apical tube in the apex of the
helmet-shaped occipital lobe, which is one and a half times as long as the
two subspherical frontal lobes. Thorax ovate, one and a half times as long
as the cephalis, with few small pores in six to eight transverse rows.

_Dimensions._--Length of the shell 0.1, breadth 0.05.

_Habitat._--Fossil in Barbados.


2. _Lithobotrys lithocorythium_, Haeckel.

  _Lithocorythium oxylophus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 78, Taf. iv. figs. 3, 4.

  ? _Lithopera oxystauros_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. iii. fig. 6.

Cephalis trilobate, with a single apical horn or a pointed tube in the apex
of the helmet-shaped occipital lobe, which is a little longer than the two
ovate frontal lobes. Thorax ovate, about as long as the cephalis, with very
numerous and small pores.

_Dimensions._--Length of the shell 0.08, breadth 0.04.

_Habitat._--Fossil in Barbados.


3. _Lithobotrys nasuta_, Ehrenberg.

  _Lithobotrys nasuta_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 76, Taf. iii. fig. 21.

Cephalis quadrilobate, with a single descending sternal or nasal tube on
the base of the anterior or frontal lobe, which is half as long as the
helmet-shaped occipital lobe and twice as large as the two lateral buccal
lobes. Thorax ovate, twice as long as the cephalis. Pores rather large,
circular.

_Dimensions._--Length of the shell 0.11, broad 0.05.

_Habitat._--Fossil in Barbados.


4. _Lithobotrys ornata_, Ehrenberg.

  _Lithobotrys ornata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 76, Taf. iii. fig. 18.

Cephalis quinquelobate, with two divergent ascending tubes, a posterior
occipital and an anterior sternal or nasal tube. Occipital lobe
campanulate, twice as large as the two frontal, and four times as large as
the two buccal lobes. Thorax ovate, twice as long as the cephalis. Pores
scarce and small. The specimen figured by Ehrenberg is very incomplete.

_Dimensions._--Length of the shell 0.09, breadth 0.05.

_Habitat._--Fossil in Barbados.


{1119}5. _Lithobotrys sphærothorax_, n. sp. (Pl. 96, fig. 15).

Cephalis trilobate, with two divergent cylindrical tubes, an ascending
apical tube in the apex of the ovate occipital lobe, and a descending
sternal or nasal tube in the campanulate frontal lobe; between the two
lobes a smaller central lobe. Thorax spherical, twice as long as the
latter. Pores very small, numerous.

_Dimensions._--Length of the shell 0.08, breadth 0.06.

_Habitat._--Western Tropical Pacific, Station 225, depth 4575 fathoms.


6. _Lithobotrys mascula_, n. sp. (Pl. 96, fig. 16).

Cephalis sexlobate, with two divergent cylindrical tubes, an ascending
apical tube in the apex of the helmet-shaped occipital lobe and a
descending sternal tube on the base, between the two kidney-shaped frontal
lobes. The latter are half as large as the odd occipital lobe and of about
the same size as the two inflated lateral buccal lobes, which are separated
by a small odd nasal lobe.

_Dimensions._--Length of the shell 0.13, breadth 0.08.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


7. _Lithobotrys orchidea_, n. sp. (Pl. 96, fig. 17).

Cephalis sexlobate, similar to the preceding species, but with five
divergent and curved cylindrical tubes, which correspond to the five spines
of _Stephanium_; an apical tube on the apex of the occipital lobe, a caudal
tube on its base, a sternal tube between the two frontal lobes, and two
paired pectoral tubes between the latter and the lateral buccal lobes.
Pores small and scarce.

_Dimensions._--Length of the shell 0.12, breadth 0.06.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Family LVIII. #PYLOBOTRYIDA#, Haeckel (_sensu emendato_).

  _Pylobotryida_, Haeckel, 1881, Prodromus, p. 440.

_Definition._--Botryodea trithalamia, the shell of which is composed of a
lobate cephalis, a thorax, and an abdomen.

The family #Pylobotryida# comprises those #Botryodea# in which the shell
exhibits two parallel transverse annular constrictions, and is divided by
these into three successive joints, corresponding to the cephalis, the
thorax, and the abdomen of the Tricyrtida. As in the latter, the abdomen is
here also a later production, arising from the terminal mouth of the
thorax; therefore the Pylobotryida must be derived phylogenetically from
the Lithobotryida.

Two genera of Pylobotryida were incompletely described in 1860 by
Ehrenberg, _Botryocyrtis_ and _Botryocampe_. We retain them here, with a
stricter definition, however. Two other genera were added in my
Prodromus--_Pylobotrys_ and _Phormobotrys_. {1120}The small number of
species here enumerated may be easily increased, since numerous forms,
belonging probably to this family, are not sufficiently known. Their study
is, however, very difficult and requires accurate examination of the tiny
shells from different sides.

The four genera of Pylobotryida, here described, represent two different
subfamilies. The terminal mouth of the abdomen remains open in the
Botryocyrtida, whilst it becomes closed by a lattice-plate in the
Botryocampida. There are in both groups shells with and without porous
tubes; the number of these tubes, and also the number and disposition of
the lobes in the cephalis, exhibits remarkable differences in the different
species of those genera, and may in future serve for their division into a
greater number of genera.

_Synopsis of the Genera of Pylobotryida._

                               { Cephalis without
  I. Subfamily Botryocyrtida.  {  porous tubes,        492. _Botryocyrtis_.
                               {
  Mouth of the abdomen open.   { Cephalis with a
                               {  variable number of
                               {  porous tubes,        493. _Pylobotrys_.

                               { Cephalis without
  II. Subfamily Botryocampida. {  porous tubes,        494. _Botryocampe_.
                               {
  Mouth of the abdomen closed  { Cephalis with a
    by a lattice-plate.        {  variable number
                               {  of porous tubes,     495. _Phormobotrys_.



Genus 492. _Botryocyrtis_,[109] Ehrenberg, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 829.

_Definition._--#Pylobotryida# without tubes on the cephalis, and with the
mouth of the abdomen open.

The genus _Botryocyrtis_, founded by Ehrenberg upon two Indian species, is
the simplest among the Pylobotryida. It may have been derived from
_Botryopyle_ by the development of an abdomen (or a third shell-joint), the
mouth of which remains open.


1. _Botryocyrtis serpentis_, Ehrenberg.

  _Botryocyrtis serpentis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. x. fig. 21.

Cephalis quadrilobate; the odd frontal and the two paired buccal lobes
subspherical, about half as large as the odd occipital lobe. Thorax
inflated, about as long as the cephalis and half as long as the ovate
abdomen. Mouth of the latter constricted, of half the breadth.

_Dimensions._--Length of the shell 0.12, breadth 0.06.

_Habitat._--Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.


{1121}2. _Botryocyrtis theocampe_, n. sp. (Pl. 96, fig. 19).

Cephalis quadrilobate; the odd frontal and the two paired buccal lobes
hemispherical, about half as large as the helmet-shaped occipital lobe.
Thorax cylindrical, of equal length and breadth, one and a half times as
broad as the cephalis and as the cylindrical abdomen. Pores rather large,
irregular, roundish.

_Dimensions._--Length of the shell 0.12, breadth 0.06.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


3. _Botryocyrtis cerebellum_, n. sp. (Pl. 96, fig. 18).

Cephalis quinquelobate; the odd frontal and the two paired buccal lobes
ovate, about half as large as the two helmet-shaped paired occipital lobes
(?). Thorax campanulate, twice as broad and long as the cephalis and as the
truncate cylindrical abdomen.

_Dimensions._--Length of the shell 0.12, breadth 0.08.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


4. _Botryocyrtis quinaria_, Ehrenberg.

  _Botryocyrtis quinaria_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. x. fig. 16.

Cephalis quinquelobate; the odd occipital lobe ovate, twice as large as
each of the other four subspherical lobes, the two anterior (or frontal) of
which are somewhat smaller than the two posterior (or buccal). Thorax
campanulate, somewhat larger than the truncate abdomen. Pores rather large,
irregular.

_Dimensions._--Length of the shell 0.09, breadth 0.05.

_Habitat._--Indian Ocean (Zanzibar and Madagascar), surface.



Genus 493. _Pylobotrys_,[110] Haeckel, 1881, Prodromus, p. 440.

_Definition._--#Pylobotryida# with tubes on the cephalis, and with the
mouth of the abdomen open.

The genus _Pylobotrys_ differs from the closely allied _Acrobotrys_, its
ancestral form, in the development of an abdomen or a third shell-joint,
the basal mouth of which remains open.


1. _Pylobotrys putealis_, n. sp. (Pl. 96, fig. 21).

Cephalis multilobate, with a single curved and descending tube on the base
of its anterior part (sternal tube). Occipital half of the cephalis divided
into three large odd lobes (the largest {1122}the apical); facial half
divided into three to five lobes, an odd frontal and one or two lateral
pairs of small buccal lobes. Thorax truncate conical, about as large as the
cephalis and larger than the truncate abdomen. Pores regular circular.

_Dimensions._--Length of the shell 0.12, breadth  0.08.

_Habitat._--Tropical Atlantic Station 347, depth 2250 fathoms.


2. _Pylobotrys fontinalis_, n. sp. (Pl. 96, fig. 20).

Cephalis trilobate, with three ovate lobes in the sagittal plane, of nearly
equal size, and two divergent cylindrical tubes conical at the base. An
ascending apical tube on the apex of the occipital lobe and a descending
sternal tube on the base of the frontal lobe. The middle lobe between the
former distinctly exhibits in the apical view (fig. 20) the collar septum
with the four cortinar pores. Thorax campanulate, larger than the cephalis
and the truncate abdomen.

_Dimensions._--Length of the shell 0.11, breadth 0.06.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


3. _Pylobotrys cerebralis_, n. sp. (Pl. 96, fig. 22).

Cephalis multilobate, with four divergent cylindrical tubes, which are
cylindrical, obliquely truncate at the mouth, and correspond in position to
the four typical spines of _Cortina_; an ascending apical tube and three
descending basal tubes (an odd caudal and two paired pectoral). The
helmet-shaped occipital lobe is about as large as the frontal half of the
cephalis, which is divided into three pairs of smaller pyriform lobes.
Thorax subspherical, about as large as the cephalis and half as large as
the inflated abdomen. Pores very scarce and small.

_Dimensions._--Length of the shell 0.15, breadth 0.08.

_Habitat._--Indian Ocean, Cocos Islands, Rabbe, surface.



Genus 494. _Botryocampe_,[111] Ehrenberg, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 829.

_Definition._--#Pylobotryida# without tubes on the cephalis, and with the
mouth of the abdomen closed.

The genus _Botryocampe_ may be derived from _Botryocyrtis_ by development
of a basal lattice-plate, closing the terminal mouth of the abdomen. It is
at the same time closely allied to the Tricyrtid _Theocapsa_, and may be
perhaps derived from this by lobation of the cephalis.


{1123}1. _Botryocampe inflata_, Ehrenberg.

  _Botryocampe inflata_, Ehrenberg, 1861, Monatsber. d. k. Akad. d. Wiss.
  Berlin, p. 296;    Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 285,
  Taf. ii. fig. 4.

  _Botryocampe inflata_, Haeckel, 1862, Monogr. d. Radiol., p. 345.

  _Lithobotrys inflata_, Bailey, 1856, Amer. Journ. Sci. and Arts, vol.
  xxii. p. 1, pl. i. fig. 15.

Cephalis trilobate, inflated, of about the same breadth and length as the
tun-shaped thorax and the hemispherical abdomen. Frontal lobes of the
cephalis ovate, a little smaller than the ovate odd occipital lobe. Pores
numerous and small.

_Dimensions._--Length of the shell 0.05 to 0.08, breadth 0.02 to 0.04.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, Stations 267 to
274, 241, 354, &c., surface, and in various depths.


2. _Botryocampe theocapsa_, n. sp.

Cephalis trilobate, half as long as the campanulate thorax, and one-third
as long as the ovate abdomen. Frontal lobes subspherical, scarcely half as
long as the helmet-shaped occipital lobe. Pores very small and scarce.

_Dimensions._--Length of the shell 0.12, breadth 0.04.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.


3. _Botryocampe galea_, Haeckel.

  _Lithobotrys galea_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.
  Wiss. Berlin, p. 83.

  _Lithocorythium galea_, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 29,
  a, b.

  _Lithocorythium galea_, Haeckel, 1862, Monogr. d. Radiol., p. 330.

Cephalis quinquelobate, about as large as the ovate thorax, and twice as
large as the hemispherical abdomen (which is identical with the "crista
obtusa finis anterioris" of Ehrenberg). Occipital lobe helmet-shaped, about
twice as long as the two pairs of lateral lobes (the superior frontal and
the inferior buccal lobes).

_Dimensions._--Length of the shell 0.08, breadth 0.04.

_Habitat._--Fossil in Barbados.


4. _Botryocampe rotalia_, n. sp. (Pl. 96, fig. 23).

Cephalis quinquelobate, half as large as the campanulate thorax and the
subspherical abdomen. Occipital lobe ovate, one and a half times as long as
the two ovate frontal lobes, and three times as long as the two
subspherical buccal lobes. Collar septum with six distinct cortinar pores
(two anterior jugular, two middle cardinal and two posterior cervical, fig.
23).

_Dimensions._--Length of the shell 0.1, breadth 0.06.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


{1124}5. _Botryocampe camerata_, n. sp. (Pl. 96, fig. 24).

Cephalis multilobate, about as long and half as broad as the irregularly
campanulate thorax, which is half as long as the subspherical large
abdomen. Occipital lobe of the cephalis helmet-shaped, larger than its
uviform frontal part, which is divided into six to eight small subspherical
lobes. In the interior of the thorax and abdomen irregularly branched rods
are visible, which divide their inner space into compartments or incomplete
chambers. Pores large, regular, circular, hexagonally framed.

_Dimensions._--Length of the shell 0.15, breadth 0.09.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 495. _Phormobotrys_,[112] Haeckel, 1881, Prodromus, p. 440.

_Definition._--#Pylobotryida# with tubes on the cephalis, and with the
mouth of the abdomen closed.

The genus _Phormobotrys_ differs from the similar and closely allied
_Pylobotrys_ in the development of a basal lattice-plate closing the
terminal mouth of the thorax, and corresponds therefore to _Lithobotrys_
among the Lithobotryida. As in the latter and in _Cannobotrys_, &c., so
here in _Phormobotrys_, different subgenera may be distinguished, according
to the different number and disposition of the radial tubes which become
developed from the lobate cephalis.


1. _Phormobotrys trithalamia_, n. sp. (Pl. 96, fig. 26).

Cephalis trilobate, with a single apical tube, which is only one-third as
long, spindle-shaped, pointed, with frontal opening. Frontal lobes ovate,
two-thirds as long as the helmet-shaped occipital lobe. Internal frontal
septum of the cephalis with four large pores. Thorax cylindrical, twice as
long as the hemispherical abdomen. Pores small and numerous, irregular,
roundish.

_Dimensions._--Length of the shell 0.16, breadth 0.05.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Phormobotrys pentathalamia_, n. sp. (Pl. 96, fig. 27).

Cephalis quinquelobate, with a single conical apical tube of the same
length, which has an obliquely truncate frontal opening. Odd frontal and
paired buccal lobes smaller than the sternal and the occipital lobe.
Internal frontal septum with six large pores. Thorax inflated, a little
larger than the subspherical abdomen. Pores subregular, circular.

_Dimensions._--Length of the shell 0.15, breadth 0.08.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


{1125}3. _Phormobotrys hexathalamia_, Haeckel.

  _Botryocampe hexathalamia_, Haeckel, 1862, Monogr. d. Radiol., p. 344,
  Taf. xii. fig. 10.

Cephalis sexlobate, with a single apical horn, which is solid, vertical,
cylindrical, pointed, only one-third as long. Frontal lobes subcylindrical,
nearly as long as the kidney-shaped occipital lobe, three to four times as
long as the small buccal lobes and the odd sternal lobe. Thorax tun-shaped,
smaller than the cephalis, larger than the hemispherical abdomen. Pores
numerous, subregular, circular.

_Dimensions._--Length of the shell 0.13 to 0.15, breadth 0.05 to 0.06.

_Habitat._--Mediterranean, Messina, surface.


4. _Phormobotrys cannothalamia_, n. sp. (Pl. 96, fig. 25).

Cephalis trilobate, of about the same breadth and length as the campanulate
thorax, which is three times as long as the flat cap-shaped abdomen. The
middle (or central) lobe of the cephalis is simple, nearly cubical, and
smaller than the ovate occipital and frontal lobe. The two latter are
prolonged into two slender cylindrical divergent tubes. Pores small and
very numerous.

_Dimensions._--Length of the shell 0.1, breadth 0.05.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


5. _Phormobotrys polythalamia_, n. sp.

Cephalis multilobate, of the same length and breadth as the subspherical
thorax, and half as long as the ovate abdomen. Occipital lobe
helmet-shaped, about as large as the frontal half of the cephalis, which is
divided into six to eight lobes (two odd and two or three pairs of lateral
lobes). Four cylindrical tubes corresponding to the four typical spines of
_Cortina_, an ascending apical and three descending basal tubes (a
posterior caudal and two anterior pectoral).

_Dimensions._--Length of the shell 0.14, breadth 0.08.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.


{1126}----


Suborder III. CYRTOIDEA, Haeckel, 1862.

  _Cyrtida_, Haeckel, 1862, Monogr. d. Radiol., pp. 272, 280.
  _Cyrtoidea_ vel _Cyrtida_, Haeckel, 1881, Prodromus, pp. 425-439.
  _Polycystina solitaria_, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad.
      d. Wiss. Berlin, pp. 53, 54.
  _Monodictya nassellaria_, Ehrenberg, 1875, Abhandl. d. k. preuss. Akad.
      d. Wiss. Berlin, pp. 156, 157.

_Definition._--NASSELLARIA with a complete lattice-shell, exhibiting a
simple or reduced cephalis, which is neither bilocular nor lobate, without
sagittal constriction.

The order #Cyrtoidea#, described by me in 1862 as the family Cyrtida, is by
far the largest of all the main groups of Radiolaria, and remarkable from
the extraordinary variety of forms and the number of species. In the
following system more than eleven hundred species are described, comprising
about one-fourth of the number of species in the whole class of Radiolaria.
This astonishing variety, however, is not effected by development of a
large number of different types, but by an extraordinary variability within
certain restricted boundaries, similar to what is seen among insects and
birds. The number of genera, therefore, is comparatively small, and they
may all be disposed into four families only, which in my Monograph (1862,
p. 280) were distinguished as Monocyrtida, Dicyrtida, Tricyrtida and
Stichocyrtida. If we divide these four groups in the following pages into
twelve families and twenty-four subfamilies, we are guided by practical
considerations only, hoping thereby to give a better survey of the
difficult labyrinth of Cyrtoidean morphology.

The #Cyrtoidea# are characterised by this wonderful richness of specific
forms not only in the present seas, but also for millions of years in the
former ages of our globe. The majority of all the fossil Radiolaria which
are now known belong to this group, and many species of it are so common
that great rocks are formed by their union. The fact was first observed by
Ehrenberg, who in his first system of _Polycystina_ (1847, _loc. cit._, p.
54) enumerated forty-four genera and two hundred and eighty-two species;
the #Cyrtoidea#, his Polycystina solitaria, form the preponderant majority
of the whole class, viz., twenty-five genera and one hundred and
ninety-three species.

In this first system (of 1847), as well as in the last systematic table of
Ehrenberg (of 1875, _loc. cit._), the Cyrtida as "Polycystina solitaria"
are opposed to all other Radiolaria, as "Polycystina composita." The former
bear the definition "Testæ siliceæ spatio interno ample pervio, aut passim
levius transverse constricto"; the latter, however, "Testæ siliceæ spatio
interno celluloso aut strictura longitudinali constricto." In reality these
definitions are insufficient, and the conclusions which Ehrenberg derived
{1127}from the organisation of the Polycystina solitaria and composita,
were quite erroneous. So also are the definitions of the three families
into which he divided the Polycystina solitaria, afterwards (in 1875)
called by him "Monodictya nassellaria." These three families were the
Halicalyptrina, Lithochytrina and Eucyrtidina. With these were also united
the three genera of #Botryodea# known to Ehrenberg (_Lithobotrys_,
_Botryocampe_, _Botryocyrtis_). We entirely separate these here from the
true Cyrtida, on account of their lobate or multilocular cephalis.

Whilst Ehrenberg only knew the skeleton of the Polycystina solitaria, the
first observations of living Cyrtida were published by Johannes Müller,
1858, in his fundamental treatise. He gave the first description and
figures of the central capsule of this group, with the characteristic lobes
developed from its basal part; and of the pseudopodia radiating on all
sides (_loc. cit._, Taf. vi.). The forms described by him were all
Mediterranean, one Dicyrtid (_Lithomelissa mediterranea_), two Tricyrtids
(_Eucyrtidium zancleum_ and _Pterocanium charybdeum_), and one Stichocyrtid
(_Lithocampe tropeziana_).

In my monograph (1862, p. 272-341) I gave a detailed description of all
known and some new Cyrtida, and characterised this family by the
fundamental monaxonial form of the shell, with two different poles (an
upper apical and a lower basal pole), and by the unipolar growth, beginning
from the apical pole. I pointed out also the peculiar structure of the
monaxonial central capsule. At that time I divided the Cyrtida into five
subfamilies, in which, however, the #Spyroidea# (= Zygocyrtida), and the
#Botryodea# (= Polycyrtida) were united with the true #Cyrtoidea#
(Monocyrtida, Dicyrtida, Stichocyrtida).

The astonishing number of new and interesting forms of Cyrtida which I
found in the rich collection of the Challenger (beginning from 1876), and
mainly in the Radiolarian ooze of the Central Pacific (Stations 263 to
274), enabled me to give in my Prodromus, in 1881, a greatly enlarged and
amended system of this important group. I separated there the #Spyroidea#
(= Zygocyrtida), and the _Botryodea_ (= Polycyrtida) from the true
#Cyrtoidea# by restricted definition, pointing out the essential
differences in the structure of the cephalis in these groups of
#Cyrtellaria#. The latter name, as here used, is therefore identical with
the "Cyrtida" of my Monograph. In the Prodromus I divided the true Cyrtida
(p. 426) into five subfamilies and thirty tribes, corresponding to the
differences in the number of the shell-joints and of the radial apophyses,
and in the shape of the closed or open mouth. These groups are here
retained, but reduced to four families and twenty-four subfamilies, since
the Tetracyrtida are better united with the Stichocyrtida (compare below).

Richard Hertwig in his work Organismus der Radiolarien (1879, pp. 74 to 86)
gave the first accurate description of the finer structure of the central
capsule of the Cyrtida, and pointed out their character as true MONOPYLEA,
with porochora and {1128}podoconus, and the peculiar shape of its nucleus.
He also published excellent figures of some interesting new species.

O. Bütschli, 1882, in his valuable paper entitled: "Beiträge zur Kentniss
der Radiolarien-Skelette, insbesondere der der Cyrtida" (Zeitschr. für
wiss. Zool., vol. xxxvi. p. 485) made an attempt at a natural
classification of the Cyrtida, which he derived from the #Spyroidea# or
Zygocyrtida. As already mentioned above, we cannot accept this essay as the
foundation of a true natural system, since the affinities of the
#Cyrtellaria# (and of the NASSELLARIA as a whole) are far more complicated
and difficult than Bütschli supposed. His views were supported by accurate
observations only on the structure of the fossil #Cyrtoidea# of Barbados;
these, however, represent the minority only of the genera, and many
interesting and important forms (mainly of true "Monocyrtida") remained
unknown to Bütschli. A great part, however, of his observations are very
useful, and his remarks on comparative morphology are very suggestive.

The #Cyrtoidea# may be divided into families and subfamilies according to
three different principles, viz., (1) the number of joints into which the
shell is divided by transverse strictures; (2) the number of radial
apophyses which arise from the shell; (3) the shape of the basal mouth,
which is either open or closed by a lattice-plate. At present every attempt
of classification in this large group must be more or less artificial,
since the affinities of the numerous smaller and larger groups are
extremely complicated, and the ontogeny, the only sure guide in this
phylogenetical labyrinth, is perfectly unknown. It seems therefore the most
convenient to employ for our artificial classification, first, the number
of shell-joints, second, the radial structure, and third, the shape of the
mouth.

A. The number of joints into which the shell is divided by transverse
constrictions, serves here for the distinction of four primary groups or
suborders of the #Cyrtoidea#, viz., (1) Monocyrtida with one joint; (2)
Dicyrtida with two joints; (3) Tricyrtida with three joints; and (4)
Stichocyrtida with four or more joints. In my Prodromus (1881, p. 426) I
divided the latter group into Tetracyrtida (with four joints), and
Stichocyrtida (with five or more joints); but these two groups may be
united, since the fourth and all the succeeding joints are of rather
indifferent shape and of little morphological value. The three first
joints, however, are usually very different and possess a high
morphological importance, so that we distinguish the first joint as
cephalis, the second as thorax, and the third as abdomen. The uppermost
transverse constriction, which separates the two first joints, cephalis and
thorax, is the collar stricture and is usually caused by an internal
fenestrated septum, the cortinar septum. The second constriction, which
separates the second and third joints (thorax and abdomen) is called the
lumbar constriction. The following constrictions (in the Stichocyrtida) are
indifferent and of little morphological interest, and require therefore no
peculiar designation.

{1129}B. The radial structure, indicated by radial apophyses arising from
the shell, offers three principal differences, according to which the whole
group of #Cyrtoidea# may be divided into three large groups or sections,
viz., (1) Pilocyrtida, or Cyrtoidea triradiata, with three radial
apophyses; (2) Astrocyrtida, or Cyrtoidea multiradiata, with numerous
radial apophyses (four to nine or more); and (3) Corocyrtida, or Cyrtoidea
eradiata, without external radial apophyses. The majority of #Cyrtoidea#
are Pilocyrtida, with three radial apophyses, which are probably homologous
to the three primary feet of the #Plectoidea# and of _Cortina_ (therefore
"cortinar feet"). The Astrocyrtida, or the #Cyrtoidea# with a variable
number of radial apophyses (at least four to six) may be derived from the
Pilocyrtida by interpolation of secondary or interradial apophyses between
the three primary or perradial apophyses. The Corocyrtida, however, or the
#Cyrtoidea# without external radial apophyses, may have originated by
reduction and loss of the latter, either from the Pilocyrtida or from the
Astrocyrtida.

C. The shape of the basal mouth in the #Cyrtoidea# exhibits two essential
differences only, viz., (1) the terminal mouth of the shell is a simple
wide opening in the Stomocyrtida, or (2) the terminal mouth is closed by a
lattice-plate, in the Clistocyrtida. As these two different cases occur in
all the twelve families, which we have distinguished according to the
differences in the number of joints and in the radial structure, we get
altogether twenty-four subfamilies which are synoptically arranged in the
following table:--

  +---------------------------+---------------------------------+
  |   Synopsis of the four    |                                 |
  | sections, twelve families |          PILOCYRTIDA.           |
  |and twenty-four subfamilies|     Cyrtoidea triradiata.       |
  |      of CYRTOIDEA.        |   (Three radial apophyses.)     |
  +---------------------------+----------------+----------------+
  |   Mouth of the shell.     |    _Aperta._   |    _Clausa._   |
  +---------------------------+----------------+----------------+
  |      MONOCYRTIDA.         |           TRIPOCALPIDA.         |
  |(Cyrtoidea monothalamia).  |  Archipilida.  |  Archiperida.  |
  +---------------------------+----------------+----------------+
  |       DICYRTIDA.          |           TRIPOCYRTIDA.         |
  |(Cyrtoidea dithalamia).    |  Sethopilida.  |  Sethoperida.  |
  +---------------------------+----------------+----------------+
  |       TRICYRTIDA.         |            PODOCYRTIDA.         |
  | (Cyrtoidea trithalamia).  |   Theopilida.  |  Theoperida.   |
  +---------------------------+----------------+----------------+
  |     STICHOCYRTIDA.        |            PODOCAMPIDA.         |
  |(Cyrtoidea polythalamia).  |  Stichopilida. | Stichoperida.  |
  +---------------------------+---------------------------------+
  |                           |          ASTROCYRTIDA.          |
  |                           |     Cyrtoidea multiradiata.     |
  |                           |(Four to nine or more apophyses.)|
  +---------------------------+----------------+----------------+
  |   Mouth of the shell.     |    _Aperta._   |    _Clausa._   |
  +---------------------------+----------------+----------------+
  |      MONOCYRTIDA.         |           PHÆNOCALPIDA.         |
  |(Cyrtoidea monothalamia).  | Archiphormida. | Archiphænida.  |
  +---------------------------+----------------+----------------+
  |       DICYRTIDA.          |           ANTHOCYRTIDA.         |
  |(Cyrtoidea dithalamia).    | Sethophormida. | Sethophænida.  |
  +---------------------------+---------------------------------+
  |       TRICYRTIDA.         |           PHORMOCYRTIDA.        |
  | (Cyrtoidea trithalamia).  |  Theophormida. |  Theophænida.  |
  +---------------------------+----------------+----------------+
  |     STICHOCYRTIDA.        |           PHORMOCAMPIDA.        |
  |(Cyrtoidea polythalamia).  | Stichophormida.| Stichophænida. |
  +---------------------------+----------------+----------------+
  |                           |          COROCYRTIDA.           |
  |                           |      Cyrtoidea eradiata.        |
  |                           |     (No radial apophyses.)      |
  +---------------------------+----------------+----------------+
  |   Mouth of the shell.     |    _Aperta._   |    _Clausa._   |
  +---------------------------+----------------+----------------+
  |      MONOCYRTIDA.         |           CYRTOCALPIDA.         |
  |(Cyrtoidea monothalamia).  |   Archicorida. |  Archicapsida. |
  +---------------------------+----------------+----------------+
  |       DICYRTIDA.          |           SETHOCYRTIDA.         |
  |(Cyrtoidea dithalamia).    |   Sethocorida. | Sethocapsida.  |
  +---------------------------+---------------------------------+
  |       TRICYRTIDA.         |           THEOCYRTIDA.          |
  | (Cyrtoidea trithalamia).  |   Theocorida.  |  Theocapsida.  |
  +---------------------------+----------------+----------------+
  |     STICHOCYRTIDA.        |           LITHOCAMPIDA.         |
  |(Cyrtoidea polythalamia).  |  Stichocorida. | Stichocapsida. |
  +---------------------------+----------------+----------------+

{1130}The cephalis, or the first shell-joint of the #Cyrtoidea#, is in the
majority homologous with the cephalis of the #Spyroidea#, from which it
differs in the reduction of the sagittal ring and the absence of the
corresponding sagittal constriction; its cavity is therefore simple, not
bilocular. Its homology with the original cephalis of the #Spyroidea#
cannot be doubted, when its base exhibits the typical basal pores of the
Semantida. But in many cases these are wanting, and in a great number of
#Cyrtoidea# (mainly of Monocyrtida) there is more or less evidence that the
original cephalis is lost, and that the real first joint is the thorax, the
original second joint. At present it is quite impossible to distinguish
between the former and the latter shells, and therefore in the following
descriptions the first joint is always named cephalis and the second
thorax. In future, when the affinities of the #Cyrtoidea# become better
known, it will be necessary to distinguish the "Archicephalis," or true
cephalis of all #Spyroidea# and of the majority of #Cyrtoidea#, from the
"Pseudocephalis" or the false cephalis of the minority (_e.g._, of many
Monocyrtida aperta, Archipilida, Archiphormida, Archicorida, &c.).

The thorax, or the second shell-joint of the #Cyrtoidea#, is in the
majority homologous with the thorax of the Phormospyrida and Androspyrida,
and therefore developed by apophyses, which arise from the base of the
cephalis and become united by transverse branches forming a lattice-plate.
Its size is generally in inverse proportion to that of the cephalis. The
more the cephalis becomes reduced, the more the thorax is developed. Its
form is very variable, usually three-sided pyramidal or prismatic in the
triradiate, polyhedral in the multiradiate, and conical or cylindrical in
the eradiate #Cyrtoidea#. Its terminal mouth is either a simple wide
opening, or closed by a lattice-plate. In the majority of #Cyrtoidea# the
thorax is separated from the cephalis not only by the external collar
constriction, but also by the internal cortinar septum, a horizontal
lattice-plate which exhibits the typical basal pores of the Semantida
(usually two smaller jugular and two larger cardinal pores). But this
septum is often reduced or perfectly lost, and then the external collar
constriction alone indicates the separation of the cephalis and the thorax.

The abdomen, or the third shell-joint of the #Cyrtoidea#, absent in the
Monocyrtida and Dicyrtida (as also in all #Spyroidea#), occurs constantly
in all Tricyrtida and Stichocyrtida. It is a simple large chamber in the
Tricyrtida, but forms an annulated body, composed of a variable number of
successive joints, in the Stichocyrtida. The constrictions between these
joints, and also the lumbar constriction, between abdomen and thorax, are
usually provided with a lattice-girdle, projecting into the cavity of the
shell, like a diaphragm. Usually this horizontal girdle bears only a single
circle of pores, rarely two or more. In many #Cyrtoidea# it is replaced by
a solid horizontal ring of silex, and often it is wanting. It originates by
the insertion of the following shell-joint, which takes place not on the
terminal mouth of the preceding joint, but somewhat above it.

{1131}The annular joints of the Stichocyrtida succeeding the third joint,
and very variable in number, may be regarded either as a series of new
postabdominal chambers, succeeding the true abdomen, or as secondary joints
of the annulated abdomen itself. The latter view may be sustained by the
fact that these joints are usually of an indifferent shape, and do not
possess the characteristic features which we find in the first three
joints, the abdomen, the thorax and the cephalis.

The lattice-work of the shell exhibits in the #Cyrtoidea# an extraordinary
variety, similar to that of the #Sphæroidea#; it serves in the first place
for the distinction of species. The three first joints of the shell are
often distinguished by the different character of the lattice-work. The
cephalis has usually very small and simple pores. The lattice-work of the
thorax is often characterised by radial structures. The pores of the
abdomen are usually very numerous and regular. The numerous joints in the
annulated abdomen of the Stichocyrtida commonly exhibit little variety.

The closure of the mouth, effected by a convex or horizontal terminal
lattice-plate, has a different signification in the Monocyrtida and in the
jointed #Cyrtoidea#. In the Monocyrtida clausa this closing plate is the
original cortinar plate or the basal plate of the cephalis. In the jointed
#Cyrtoidea#, however, the lattice-plate which closes the terminal mouth of
the thorax or of the abdomen (of the last annular joint in the
Stichocyrtida), is produced by central union of the convergent edges, which
grow centripetally from the margin of the mouth of the last joint towards
its centre.

The radial apophyses arising from the shell of the #Cyrtoidea# may probably
be always derived from that tripodal structure which is found in all
#Plectoidea#, in _Cortina_ and _Cortiniscus_ among the #Stephoidea#, and in
the majority of #Spyroidea#. Therefore the prototype of this radial
structure would be _Plagoniscus_ and _Cortina_, with four radial spines
united in a common point, the cortinar centrum; an ascending apical horn
and three descending basal feet. The odd posterior or caudal foot is
usually similar in shape to the two paired anterior or pectoral feet, but
may be distinguished from these latter by its relation to the apical horn.
Very frequently an internal vertical free columella arises in the cephalis,
or instead of it an ascending rib in the dorsal wall of the cephalis, which
connects the base of the apical horn with the origin of the caudal foot.
This is probably the remaining part of the sagittal ring. More rarely also
a part of the ventral rod of the latter is preserved, or on the anterior
pole of the basal rod of the cephalis an ascending procolumella arises
which is inserted on the frontal face of the cephalis, and sometimes
prolonged into a nasal horn (the rod, C, of Bütschli). These two odd horns,
the posterior apical horn and the anterior nasal horn, are usually
different and divergent. In some genera a variable number of accessory
radial horns is developed on the convex face of the cephalis. In many
hornless genera the free apical horn is lost, but not unfrequently the
columella is preserved which connects the caudal foot with that point of
the cephalis, in which formerly the apical horn was inserted.

{1132}The three primary radial beams, corresponding to the three basal feet
of _Plectaniscus_ and _Cortina_, exhibit in the #Cyrtoidea# the greatest
variety in form and size, and chiefly in their relation to the shell, the
latter serving mainly for the distinction of genera. Originally these three
cortinar beams arise from the basal plate of the cephalis, the odd caudal
foot appearing as a prolongation of the basal rod of that plate, and the
paired pectoral feet as prolongations of its coracal rods (between the
jugular and cardinal pores). The lattice-work of the thorax is developed
usually between the three cortinar feet, more rarely inside or outside of
them. Therefore the three beams appear commonly as three divergent ribs in
the wall of the thorax, and continue over its basal mouth as three free
terminal feet. With the increasing length of the shell and the number of
its joints the three radial ribs are also prolonged, and their free distal
ends may be prominent at very different points, either as three lateral
wings or as three terminal feet. These are either solid spines or
lattice-plates, sometimes more or less ramified.

The three radial apophyses are prevalent in the majority of the
#Cyrtoidea#, which we call "Pilocyrtida" (or Cyrtoidea triradiata). Their
number increases in the Astrocyrtida (or Cyrtoidea multiradiata). The most
frequent cases of multiplication are here caused by the development of six
or nine radial apophyses; these may be enclosed ribs, or lateral wings, or
terminal feet. In the sexradial #Cyrtoidea# there are three secondary or
interradial apophyses interpolated between the three primary or perradial;
in the nine-radial #Cyrtoidea#, however, there are six adradial apophyses
interpolated.

A third and last great group is formed by the Corocyrtida or Cyrtoidea
eradiata. These exhibit no radial apophyses, neither enclosed ribs, nor
free lateral wings, nor terminal feet. But in a great number of them
internal traces of an original triradiate structure are visible, mainly in
the cortinar septum between cephalis and thorax; this often exhibits three
or four, and sometimes six cortinar or collar pores, of the same typical
shape as in the triradial #Spyroidea#. Sometimes even an internal columella
with three radial branches is preserved, as in _Axocorys_. It is therefore
very probable that a great part of these Cyrtoidea eradiata (if not all)
may be derived from triradiate or multiradiate ancestral forms, by
reduction and loss of the radial apophyses. In another part of this group,
mainly in the Monocyrtida eradiata (Cyrtocalpida) it is possible, or even
probable, that their eradiate shell has originated independently from
Nassellida, and that they have no true relation to radial #Cyrtoidea#.

_The Central Capsule_ of the #Cyrtoidea#, first observed by J. Müller
(1858), and more fully described in my Monograph (1862), was very
accurately examined by Richard Hertwig (1879). His observations were
confirmed by numerous new forms, which I was able to examine in
well-preserved preparations of the Challenger. The central capsule,
according to these, exhibits the same typical shape, which is
characteristic of all MONOPYLEA (with porochora and podoconus), and may be
derived with the latter from the common ancestral forms, _Cystidium_ and
_Nassella_ (= the skeletonless Nassellida). In {1133}the majority, however,
of #Cyrtoidea#, the capsule develops on its basal face a number of
depending lobes, as were also found in some #Spyroidea# (and probably also
#Botryodea#). In this respect we may distinguish two main forms of the
capsule in the #Cyrtellaria#, viz., the primary simple, not lobate form,
and the secondary lobate form. The central capsule is originally always
enclosed in the cephalis, and has there a simple, subspherical, ellipsoidal
or ovate form. As soon as their growth increases, and the enclosing
cephalis becomes too narrow, it sends out prolongations in the form of
basal lobes, which depend from its base, and proceed through the pores of
the basal lattice of the cephalis, or the cortinar pores. In the great
majority of #Cyrtoidea# in which the capsule was observed, either three or
four such lobes were seen (already described by J. Müller). Of course this
number depends upon the number of cortinar pores, which is either three or
four; therefore in the #Cyrtoidea# with three pores in the cortinar plate,
we find three lobes of the central capsule (an odd posterior and two paired
anterior); in the #Cyrtoidea#, however, with four pores in the cortinar
plate (the majority) we find four lobes of the central capsule (two smaller
anterior jugular and two larger posterior cardinal lobes). Usually each
lobe is ovate or pear-shaped and encloses a large oil-globule, and often
also an apophysis of the cell-nucleus.


----


Section I. MONOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., pp. 280, 281.

_Definition._--Cyrtoidea monothalamia, with simple, not jointed shell (or
cephalis), without transverse constrictions.

_Synopsis of the three Families and six Subfamilies of Monocyrtida._

  Family LIX. Tripocalpida.  } Mouth open,    1. Archipilida.
                             }
  Three radial apophyses.    } Mouth closed,  2. Archiperida.

  Family LX. Phænocalpida.   } Mouth open,    3. Archiphormida.
                             }
  Numerous radial apophyses. } Mouth closed,  4. Archiphænida.

  Family LXI. Cyrtocalpida.  } Mouth open,    5. Archicorida.
                             }
  No radial apophyses.       } Mouth closed,  6. Archicapsida.



Family LIX. #TRIPOCALPIDA#, n. fam.

  _Archipilida et Archiperida_, Haeckel, 1881, Prodromus, pp. 427, 429.

_Definition._--Monocyrtida triradiata. (#Cyrtoidea# with a simple, not
jointed shell, representing a simple cephalis, with three radial
apophyses.)

{1134}The family Tripocalpida, composed of the Archipilida and Archiperida
of my Prodromus, comprises those #Cyrtoidea# in which the lattice-shell is
quite simple, without transverse constriction, and bears three radial
apophyses. The two subfamilies differ in the shape of the basal mouth,
which in the Archipilida is a simple wide opening, in the Archiperida
closed by a lattice-plate; the former are here divided into eight, the
latter into seven different genera.

Only three species of this family were hitherto described, all three
belonging to the Archipilida, viz., (1) _Tripocalpis galea_ (fossil in
Barbados, figured by Ehrenberg, 1875, as _Halicalyptra galea_), (2)
_Tripodiscium campanula_ (fossil in Sicily, figured by Stöhr, 1880, as
_Carpocanium_); and (3) _Tridictyopus elegans_, of which Richard Hertwig
gave an excellent description in 1879, with an accurate figure of the
central capsule. All the other species of the family (seventy) are new.

The shell in the majority of Tripocalpida is ovate or campanulate,
sometimes conical or three-sided pyramidal. Three radial apophyses are
constantly distinct, either three lateral wings or three terminal feet;
these are usually solid spines, rarely lattice-plates. The top of the shell
usually bears an apical horn, rarely two or more horns; often the horn is
wanting. The lattice-work of the shell is very various in the different
species, and often of a remarkable structure (Pl. 51, figs. 6-8; Pl. 98,
figs. 4-8). The cavity of the shell is in all Archipilida, and in a part of
the Archiperida (_Peridium_, _Archipera_, _Archibursa_) quite simple. In
the other part of the Archiperida, however, constituting the peculiar group
of Euscenida (genera 504-507), a vertical columella arises in the centre of
the basal plate, and is prolonged upwards in the apical horn; this
columella is either simple (_Euscenium_, _Archiscenium_) or branched
(_Cladoscenium_, _Pteroscenium_); in the latter case the ascending branches
are disposed in triradiate verticils and are inserted on the inner face of
the shell (compare Pl. 53, figs. 11-16, and Pl. 98, figs. 1-4).

The phylogenetic origin of the Tripocalpida may be very divergent, and
their morphological affinity to the other #Nassellaria# is a very
complicated problem. The Euscenida (genera 504-507) may be derived directly
from the Plagonida (_Plagoniscus_) or Plectanida (_Plectaniscus_). The
Archibursida (genera 508-510) however, manifest a closer affinity to the
Tripospyrida, and may be derived from them by reduction of the sagittal
ring and constriction. In these two groups of Archiperida the shell may be
regarded as a true cephalis. In the Archipilida, however, where the shell
has a wide basal opening and the three radial ribs arise originally from
the base of the apical horn, the shell itself may correspond to the thorax
of the Dicyrtida, and may be derived from these by loss of the cephalis.
This is the more probable, as sometimes a small remnant of the reduced
cephalis is preserved (Pl. 98, fig. 8). None of these difficult questions
can be answered until a much closer morphological knowledge of the
Tripocalpida is acquired.

{1135}_Synopsis of the Genera of Tripocalpida._

  -------------------------------------------------------------------------
  I. Subfamily Archipilida. Basal mouth of the shell a simple wide opening.
                            --------------------
  Shell with three lateral ribs or wings, with or without terminal feet.
  -------------------------------------------------------------------------
                           { Apex with a horn,     496. _Tripocalpis_.
  Three terminal feet.     {
                           { No apical horn,       497. _Tripodonium_.

  Six to nine or more      } No apical horn,       498. _Tripterocalpis_.
   terminal feet.          }

  No terminal feet.        { Apex with a horn,     499. _Trissopilium_.
                           {
                           { No apical horn,       500. _Archipilium_.
  -------------------------------------------------------------------------
  Shell without lateral ribs or wings but with three terminal feet.
  -------------------------------------------------------------------------
  Feet simple or           } Apex with a horn,     501. _Tripilidium_.
   branched, not latticed. }
                           } No apical horn,       502. _Tripodiscium_.

  Feet latticed.             Apex with a horn,     503. _Tridictyopus_.
  -------------------------------------------------------------------------
  II. Subfamily Archiperida.
      Basal mouth of the shell closed by a lattice-plate.
                            --------------------
      Shell in its axis with a free (simple or branched) internal
      columella,
         prolonged into an apical horn.
  -------------------------------------------------------------------------
  Shell with three         } Columella simple,     504. _Euscenium_.
   free feet, without      }
   lateral lattice-wings.  } Columella branched,   505. _Cladoscenium_.

  Shell with three         } Columella simple,     506. _Archiscenium_.
   lateral lattice-wings,  }
   connecting the three    } Columella branched,   507. _Pteroscenium_.
   feet with the horn.     }
  -------------------------------------------------------------------------
  Shell with simple cavity, without free columella. Three free basal feet.
  -------------------------------------------------------------------------
  One apical horn,                                 508. _Peridium_.

  Two or more horns,                               509. _Archipera_.

  No apical horn,                                  510. _Archibursa_.



Subfamily 1. ARCHIPILIDA, Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Tripocalpida# with the basal mouth of the shell open (vel
Monocyrtida triradiata aperta).



Genus 496. _Tripocalpis_,[113] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archipilida# (vel Monocyrtida triradiata aperta) with three
lateral ribs prolonged into three terminal feet. Apex with a horn.

The genus _Tripocalpis_ opens the series of Archipilida, or of those
Monocyrtida in which the monothalamous shell exhibits a distinct triradial
structure, and a simple open mouth, without cortinar lattice. _Tripocalpis_
is probably the most primordial of the Archipilida, and has three lateral
ribs, which are prolonged into three free terminal {1136}feet, and
connected in the apex of the pyramidal or campanulate shell with the apical
horn. It may probably be derived from _Dictyophimus_ by loss of the
cephalis. The central capsule is simple, spherical, or ellipsoidal.


1. _Tripocalpis plectaniscus_, n. sp.

Shell three-sided pyramidal, smooth, about as long as broad, with irregular
polygonal pores and thin bars. Apical horn stout, three-sided pyramidal,
about as long as the shell. From the three edges of its base arise three
prominent straight radial ribs, which are prolonged into three large
divergent feet, of equal size and the same form as the horn.

_Dimensions._--Shell 0.1 diameter, horn and feet 0.12.

_Habitat._--Tropical Pacific (Philippine Sea), Station 206, depth 2100
fathoms.


2. _Tripocalpis galea_, Haeckel.

  _Halicalyptra galea_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 74, Taf. ii. fig. 10.

Shell campanulate, rough, about as long as broad, with irregular roundish
pores and thick bars. Apical horn stout, three-sided pyramidal, scarcely
one-fourth as long as the shell. Beyond its base there arise three
prominent, slightly curved lateral ribs, which are prolonged into three
pyramidal, slightly divergent stout feet, somewhat shorter than the shell.

_Dimensions._--Shell 0.08 to 0.09 diameter, horn 0.02, feet 0.07.

_Habitat._--Fossil in Barbados.


3. _Tripocalpis tricostata_, n. sp.

Shell ovate campanulate, one and a half times as long as broad, with
regular circular pores, disposed in alternate longitudinal rows. Apical
horn three-sided pyramidal, stout, half as long as the shell. In the middle
of the shell there arise three wing-like lateral ribs, which are prolonged
into three broad, slightly curved, divergent terminal feet.

_Dimensions._--Shell 0.12 long, 0.08 broad, horn and feet 0.06 to 0.08.

_Habitat._--Fossil in Barbados.


4. _Tripocalpis triserrata_, n. sp. (Pl. 51, fig. 6).

Shell ovate, nearly twice as long as broad. The three sides of the shell,
between the three large ribs, are provided each with nine delicate
parallel, longitudinal, slightly curved ribs, alternating with ten
longitudinal rows of regular circular pores about as broad as the bars.
Apical horn short and broad, three-sided pyramidal; from the three edges of
its base there arise three wing-like serrate main ribs, which are prolonged
into three short pyramidal terminal feet.

_Dimensions._--Shell 0.12 long, 0.07 broad, horn and feet 0.01.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


{1137}5. _Tripocalpis cortinaris_, n. sp. (Pl. 97, fig. 3).

Shell hemispherical, one and a half times as broad as long, with regular,
circular, hexagonally framed pores, Apical horn stout, three-sided
pyramidal, with three serrate edges. From the base of the latter arise
three strongly dentate and curved lateral ribs, with recurved teeth, and
these are prolonged into the serrate convex edge of the three basal feet,
which are crescentic and twice as long as the shell.

_Dimensions._--Shell 0.07 long, 0.1 broad; horn 0.06 long, feet 0.14 long.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.



Genus 497. _Tripodonium_,[114] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archipilida# (vel Monocyrtida triradiata aperta) with three
lateral ribs prolonged into three terminal feet. Apex without horn.

The genus _Tripodonium_ differs from the preceding _Tripocalpis_, its
probable ancestral form, only in the loss of the apical horn (already very
small in some forms of the latter). It bears therefore to the latter the
same relation that _Sethopilium_ does to _Dictyophimus_.


1. _Tripodonium campanulatum_, n. sp.

Shell campanulate, somewhat broader than high, with regular circular pores,
twice as broad as the bars. Three broad lateral wings, lamellar,
triangular, are prolonged over the peristome into three short triangular
lamellar feet one-fourth as long as the shell.

_Dimensions._--Shell 0.08 long, 0.09 broad; feet 0.02 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Tripodonium ovatum_, n. sp.

Shell ovate, one and one-third times as long as broad, with numerous and
small circular pores, scarcely as broad as the bars. Three prominent
longitudinal ribs, arising in the lower half of the shell-wall, are
prolonged into three divergent conical curved feet, about half as long as
the shell.

_Dimensions._--Shell 0.12 long, 0.09 broad; feet 0.06 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



Genus 498. _Tripterocalpis_,[115] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archipilida# (vel Monocyrtida triradiata aperta) with three
lateral wings and a peristomial corona of numerous terminal feet. Shell
ovate, with constricted mouth, without apical horn.

{1138}The genus _Tripterocalpis_ is distinguished from the other
Archipilida by the remarkable combination of three lateral wings and of
numerous (six to nine or more) terminal feet. It may be derived directly
from the preceding _Tripocalpis_ by multiplication of the terminal feet.
These are sometimes obliquely directed. The central capsule is ellipsoidal
or ovate, and fills up the greater part of the shell.


1. _Tripterocalpis phylloptera_, n. sp. (Pl. 51, fig. 1).

Shell slender, ovate, nearly twice as long as broad. Pores circular, of
different sizes and at unequal distances. Along the lower half of the shell
there arise three broad triangular lamellar wings. Peristome with twelve
conical, nearly parallel and vertical feet, about one-sixth as long as the
shell.

_Dimensions._--Shell 0.2 long, 0.12 broad; wings 0.1 long, feet 0.03 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Tripterocalpis conoptera_, n. sp. (Pl. 51, fig. 2).

Shell ovate, nearly as broad as long. Pores regular, circular, quincuncial,
twice as broad as the bars. In the middle of the shell there arise three
conical, smooth, divergent wings, about half as long as the shell.
Peristome with six short triangular, oblique, convergent feet.

_Dimensions._--Shell 0.16 long, 0.14 broad; wings 0.09 long; feet 0.02
long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


3. _Tripterocalpis ogmoptera_, n. sp. (Pl. 51, figs. 3-5).

Shell ovate, nearly as broad as long. Pores small and numerous, circular or
roundish, partly confluent, double-contoured (fig. 4). In the middle of the
shell there arise three very large conical divergent wings, which are
longitudinally striped and longer than half the shell. Peristome with nine
short triangular, oblique, convergent feet.

_Dimensions._--Shell 0.18 long, 0.16 broad; wings 0.12 long, feet 0.02
long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 499. _Trissopilium_,[116] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archipilida# (vel Monocyrtida triradiata aperta) with three
lateral ribs or wings. Mouth smooth, without terminal feet. Apex with a
horn.

The genus _Trissopilium_ and the following nearly allied _Archipilium_
differ from the other Archipilida in the absence of terminal feet, the
peristome being quite simple, and truncate. But there are three lateral
wings, arising either from the apex or from the lateral sides of the
monothalamous shell. _Trissopilium_ may perhaps be derived from
_Lithomelissa_ by reduction of the cephalis.


{1139}1. _Trissopilium tetraplecta_, n. sp.

Shell in the upper half three-sided pyramidal, in the lower half inversely
hemispherical, of equal length and breadth. Pores irregular, roundish, in
the upper half larger. From the apex there diverge four equal, straight and
stout, three-sided pyramidal spines, one of which is vertically ascending
(the horn), the three others obliquely descending (the wings). The distal
half of the latter is free, whilst the proximal half forms three ribs,
enclosed in the shell-wall. Mouth constricted, half as broad as the shell.

_Dimensions._--Shell 0.08 long and broad, horn and wings 0.1 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


2. _Trissopilium lithomelissa_, n. sp.

Shell ovate, one and one-third times as long as broad. Pores circular, of
different sizes, small and numerous. Apical horn very large, straight,
cylindrical, vertical, longer than the shell. Three lateral wings shorter,
arising from the middle of the shell, conical, curved, divergent. Mouth
truncate, two-thirds as broad as the shell.

_Dimensions._--Shell 0.11 long, 0.08 broad; horn 0.13 long, wings 0.09
long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 500. _Archipilium_,[117] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archipilida# (vel Monocyrtida triradiata aperta) with three
lateral ribs or wings. Mouth truncate, without terminal feet. Apex without
horn.

The genus _Archipilium_ differs from the nearly allied _Trissopilium_, its
probable ancestral form, in the absence of the apical horn. The three
lateral wings of the ovate shell are stout spines. It may also be derived
from the similar _Sethopilium_ by reduction and loss of the cephalis.


1. _Archipilium orthopterum_, n. sp. (Pl. 98, fig. 7).

Shell ovate, smooth, nearly cylindrical, scarcely broader than the
truncate, widely open mouth. Pores numerous, irregular, roundish, of very
different sizes. Three lateral wings arising from the middle zone, twice as
long as the shell, straight, divergent, stout, cylindrical, longitudinally
striped.

_Dimensions._--Shell 0.08 long, 0.06 broad; wings 0.15 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Archipilium sigmopterum_, n. sp.

Shell ovate, smooth, nearly campanulate, of equal length and breadth, one
and one-third times as broad as the truncate, slightly constricted mouth.
Pores scarce, irregularly formed and {1140}scattered, of very different
sizes. Three lateral wings, stout, prismatic, about as long as the shell
widely divergent and S-shaped, curved.

_Dimensions._--Shell 0.08 diameter, wings 0.08 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Archipilium cyrtopterum_, n. sp.

Shell ovate, rough, twice as broad as the constricted mouth. Pores small
and numerous, subregular, circular, smaller than the bars. Three lateral
wings cylindrical, crescentic, in the upper half divergent, in the lower
convergent, one and one-half times as long as the shell.

_Dimensions._--Shell 0.09 long, 0.07 broad; wings 0.14 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.



Genus 501. _Tripilidium_,[118] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archipilida# (vel Monocyrtida triradiata aperta) without
lateral ribs, with three simple or branched terminal feet and an apical
horn.

The genus _Tripilidium_ differs from _Tripodonium_ in the absence of the
three lateral ribs, and may be derived either from this ancestral form, or
directly from _Tripospyris_ (by loss of the sagittal ring and
constriction); perhaps also from _Lychnocanium_ (by reduction of the
cephalis). We distinguish as two subgenera, _Tristylocorys_ (with simple
feet) and _Tripodocorys_ (with branched feet).



Subgenus 1. _Tristylocorys_, Haeckel.

_Definition._--Feet simple, not branched.


1. _Tripilidium cortina_, n. sp.

Shell campanulate, rough, about as long as broad. Pores subregular,
circular, larger in the middle zone, twice to three times as broad as the
bars. Mouth constricted, half as broad as the shell. Apical horn straight
and stout, three-sided pyramidal, about as long as the shell. Three feet
divergent, slightly S-shaped, curved, somewhat longer the the shell.

_Dimensions._--Shell 0.1 diameter, horn 0.09 long, feet 0.13 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Tripilidium hemisphæricum_, n. sp.

Shell hemispherical, smooth, nearly twice as broad as long. Pores large,
with thin bars, irregular, roundish, of very different sizes. Mouth wide
open. Apical horn conical, half as long as {1141}the shell. Three feet
slender cylindrical, widely divergent, curved, nearly twice as long as the
shell.

_Dimensions._--Shell 0.08 long, 0.14 broad; horn 0.05 long, feet 0.15 long.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.


3. _Tripilidium lychnocanium_, n. sp.

Shell hemispherical, thorny, one and a half times as broad as long. Pores
regular, circular, hexagonally framed, as broad as the bars. Mouth slightly
constricted. Apical horn stout and short, three-sided pyramidal. Three feet
cylindrical, straight, divergent, twice to three times as long as the
shell. (Similar to _Lychnocanium favosum_, Pl. 61, fig. 6, perhaps derived
from it by reduction of the cephalis.)

_Dimensions._--Shell 0.08 long, 0.12 broad; horn 0.02 long, feet 0.2 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


4. _Tripilidium ovatum_, n. sp.

Shell ovate, smooth, one and one half times as long as broad. Pores
regular, circular, as broad as the bars. Mouth constricted, half as broad
as the shell. Horn short, conical. Three feet conical, curved, convergent,
scarcely one-third as long as the shell.

_Dimensions._--Shell 0.15 long, 0.11 broad; horn 0.02 long, feet 0.04 long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


5. _Tripilidium clavatum_, n. sp.

Shell nearly spherical, tuberculate, a little broader than long. Pores
regular, circular, as broad as the bars. Mouth constricted, half as broad
as the shell. Apical feet and the three divergent feet of equal size and
similar form, about as long as the shell, straight, in the basal half
smooth, cylindrical, in the distal half club-shaped, dimpled. (Very similar
to _Tripospyris conifera_ and _Tripospyris eucolpos_, Pl. 84, figs. 7 and
4; but the spherical shell exhibits no trace of sagittal ring or
constriction, and the simple shell-cavity has a wide open mouth, and is not
closed by a basal plate.)

_Dimensions._--Shell 0.1 diameter, horn and feet 0.08 to 0.09 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


6. _Tripilidium costatum_, n. sp. (Pl. 98, figs. 8, 8_a_, 8_b_).

Shell ovate, spinulate and costate, nearly twice as broad as long. Surface
with fifteen to twenty prominent longitudinal ribs, which are convergent
towards each pole and elegantly denticulate. The deep furrows between them
are divided by delicate, parallel, transverse ribs into numerous short and
broad dimples (thirty to forty in each furrow); each dimple contains a
small pore, like a transverse {1142}fissure. The apex bears a short and
stout, three-sided pyramidal horn, the hollow base of which is closed by a
small cortinar septum with three collar pores (fig. 8_b_). This seems to
indicate a rudimentary cephalis and the derivation of this species from
_Lychnocanium_ (Pl. 61). Peristome constricted, only one-fourth as broad as
the shell, with three short, conical, nearly vertical feet. The central
capsule (fig. 8_a_) in the specimen examined was well preserved,
hemispherical, not lobate, and filled up the upper half of the shell-cavity
(beyond the rudiment of the cortinar septum).

_Dimensions._--Shell 0.2 long, 0.12 broad; horn 0.01 long, feet 0.02 long.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


7. _Tripilidium elongatum_, n. sp.

Shell elongate, smooth, nearly cylindrical, in the upper third conical.
Pores small and numerous, regular, circular, half as broad as the bars,
disposed in about thirty longitudinal alternating rows. Peristome scarcely
constricted. The apical horn and the three parallel feet are of equal size
and similar form, straight, conical, one-sixth as long as the shell.

_Dimensions._--Shell 0.12 long, 0.06 broad; horn and feet 0.02 long.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Tripodocorys, Haeckel_, 1881, Prodromus, p. 428.

_Definition._--Feet forked or branched.


8. _Tripilidium dichopodium_, n. sp.

Shell hemispherical, nearly twice as broad as long, smooth. Pores
irregular, roundish, twice to four times as broad as the bars. Mouth wide
open. Apical horn spindle-shaped, half as long as the shell. Three feet
cylindrical, nearly straight and parallel, as long as the shell, forked at
the distal end. (Exhibits an external similarity to _Tripospyris semantis_,
Pl. 84, fig. 2, but has no trace of sagittal ring and constriction, and the
simple shell-cavity has a wide open mouth.)

_Dimensions._--0.06 long, 0.1 broad; horn 0.03 long, feet 0.07 long.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


9. _Tripilidium cladopodium_, n. sp.

Shell campanulate, rough, about as long as broad. Pores subregular,
circular, as broad as the bars. Mouth slightly constricted. Apical horn and
three divergent feet of nearly equal size and form, three-sided prismatic,
straight and stout, irregularly dentate and branched, somewhat longer than
the shell.

_Dimensions._--Shell 0.08 diameter; horn and feet 0.1 to 0.12 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.



{1143}Genus 502. _Tripodiscium_,[119] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archipilida# (vel Monocyrtida triradiata aperta) without
lateral ribs and apical horn, with three simple or branched terminal feet.

The genus _Tripodiscium_ may be derived either from the preceding
_Tripilidium_ by loss of the apical horn, or from the nearly related
_Tristylospyris_ by loss of the sagittal ring and constriction. Some forms
of the latter genus can scarcely be distinguished from similar species of
the former.



Subgenus 1. _Tripodiscinus_, Haeckel.

_Definition._--Feet simple, not branched nor forked.


1. _Tripodiscium tristylospyris_, n. sp.

Shell subspherical, with regular, circular pores, twice as broad as the
bars. Mouth constricted, half as broad as the shell, with three short
spindle-shaped feet, which are nearly parallel and vertical, half as long
as the shell. (Similar to _Tristylospyris scaphipes_, Pl. 84, fig. 13, but
without sagittal ring and constriction.)

_Dimensions._--Shell 0.08 long, 0.07 broad; feet 0.04 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


2. _Tripodiscium ovatum_, n. sp.

Shell ovate, rough, nearly as broad as long. Pores regular circular,
double-contoured, twice as broad as the bars. Mouth constricted, one-third
as broad as the shell, with three convergent short triangular feet.

_Dimensions._--Shell 0.1 long, 0.09 broad; feet 0.02 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Tripodiscium clavatum_, n. sp.

Shell ovate, smooth, one and a half times as long as broad. Pores irregular
roundish, of different sizes. Mouth constricted, two-thirds as broad as the
shell, with three divergent, straight club-shaped feet, nearly as long as
the shell.

_Dimensions._--Shell 0.12 long, 0.08 broad; feet 0.1 long.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


{1144}4. _Tripodiscium campanula_, Haeckel.

  _Carpocanium campanula_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf.
  iii. fig. 9.

Shell campanulate or subspherical, smooth, about as long as broad. Pores
small, regular circular, as broad as the bars. Mouth constricted, about
half as broad as the shell, with three short conical descending feet.

_Dimensions._--Shell 0.06 long, 0.05 broad; feet 0.02 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms; fossil in
Sicily.



Subgenus 2. _Tripodisculus_, Haeckel.

_Definition._--Feet branched or forked.


5. _Tripodiscium furcatum_, n. sp.

Shell ovate, rough, nearly as broad as long. Pores subregular, circular,
twice as broad as the bars. Mouth constricted, two-thirds as broad as the
shell, with three divergent parallel and vertical feet, which are as long
as the shell, and forked at the distal end.

_Dimensions._--Shell 0.09 long, 0.08 broad; feet 0.07 long.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.


6. _Tripodiscium ramosum_, n. sp.

Shell ovate, tuberculate, nearly as broad as long. Pores irregular,
roundish, of very different sizes. Mouth constricted, half as broad as the
shell, with three large, divergent, irregularly branched feet, nearly twice
as long as the shell. (Similar to _Tristylospyris ramosa_, Pl. 52, fig. 23,
but without sagittal ring and constriction.)

_Dimensions._--Shell 0.07 long, 0.06 broad; feet 0.15 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


7. _Tripodiscium sphærocephalum_, n. sp. (Pl. 52, fig. 21).

Shell subspherical, rough, with circular pores of different sizes. Mouth
constricted, circular, simple, two-thirds as broad as the shell, with three
large divergent feet, which are three-sided prismatic, irregularly
branched, and twice as long as the shell.

_Dimensions._--Shell 0.07 long, 0.08 broad; feet 0.12 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



{1145}Genus 503. _Tridictyopus_,[120] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archipilida# (vel Monocyrtida triradiata aperta) with three
latticed terminal feet. Shell ovate or subconical, with an apical horn.

The genus _Tridictyopus_ differs from the nearly allied _Tripilidium_ in
the possession of three large fenestrated shovel-shaped feet, forming
direct prolongations of the large conical shell. The lattice work exhibits
a peculiar elegant structure recurring in the similar, perhaps nearly
related, _Cephalospyris_ (Pl. 83, fig. 10; Pl. 96, fig. 28). The central
capsule is large, ellipsoidal or ovate, and fills up the greater part of
the shell cavity (compare R. Hertwig, 1879, _loc. cit._, p. 75).


1. _Tridictyopus vatillum_, n. sp. (Pl. 51, fig. 8).

Shell campanulate, about as long as broad (excluding horn and feet). Pores
irregular, polygonal, in the middle part more regular, triangular. Horn
short and stout, three-sided pyramidal. Three feet large, triangular,
shovel-shaped, about half as long as the shell.

_Dimensions._--Shell 0.14 long, 0.15 broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


2. _Tridictyopus conulus_, n. sp. (Pl. 51, fig. 7).

Shell campanulate conical, about one and a half times as long as broad
(excluding horn and feet). Pores mostly triangular, disposed in subregular
hexagonal figures, which are separated by bands of smaller irregular
polygonal pores. Horn short and stout, three-sided pyramidal. Three feet
triangular shovel-shaped, convergent, about one-sixth as long as the shell.

_Dimensions._--Shell 0.3 long, 0.2 broad; horn 0.04 long, feet 0.05 long.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.


3. _Tridictyopus elegans_, R. Hertwig.

  _Tridictyopus elegans_, R. Hertwig, 1879, Organismus d. Radiol., p. 75,
  Taf. vii. fig. 3, 3_a_, 3_b._

Shell slender, conical, campanulate, about twice as long as broad
(excluding horn and feet). Most pores subregular triangular, with some
irregular polygonal ones intermingled. The horn in the two observed
specimens was broken off, together with the conical apex of the shell.
Three feet triangular shovel-shaped, about one-sixth as long as the shell.

_Dimensions._--Shell 0.3 long, 0.15 broad; feet 0.05 long.

_Habitat._--Mediterranean (Messina), R. Hertwig, surface.



{1146}Subfamily 2. ARCHIPERIDA, Haeckel, 1881, p. 429.

_Definition._--#Tripocalpida# with the basal mouth of the shell fenestrated
(vel Monocyrtida triradiata clausa).



Genus 504. _Euscenium_,[121] n. gen.

_Definition._--#Archiperida# (vel Monocyrtida triradiata clausa) with a
free simple internal columella, prolonged into an apical horn. Three basal
feet free, without lateral wings.

The genus _Euscenium_ and the three following nearly allied genera form
together the remarkable small group of Euscenida, probably one of the
oldest and most primitive of all #Cyrtoidea#, and perhaps the common root
of this suborder, arising directly from the #Plectoidea#. The simple
skeleton is composed of four radial beams united in one point (the cortinar
centrum). Three beams are directed downwards, and form three divergent
basal feet; the fourth beam is directed upwards and represents an apical
horn; its basal part is enclosed as "columella" in the cavity of the simple
shell, the lattice-work of which connects the four spines (compare above,
_Plectaniscus_, p. 924). In the genus _Euscenium_, the simplest of all, the
columella is simple, and the three feet also simple, without wings.



Subgenus 1. _Euscenarium_, Haeckel.

_Definition._--Three feet simple, not branched.


1. _Euscenium plectaniscus_ (Pl. 98, fig. 1).

Shell three-sided pyramidal, thorny, about as long as broad, with three
dentate edges. Framework very loose, with irregular polygonal meshes; in
the middle of each of the three triangular sides a horizontal band of
denser network. Basal plate with three very large simple collar-holes. The
apical horn and the three feet are three-sided pyramidal, about half as
long as the columella, with three prominent irregularly dentate edges. The
horn is straight, whilst the three feet are hook-shaped, its distal end
being curved downwards and inwards.

_Dimensions._--Shell 0.11 long, 0.13 broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


2. _Euscenium archicyrtis_, n. sp.

Shell three-sided pyramidal, smooth, nearly as long as broad, with three
straight edges connected by irregular loose framework with polygonal
meshes. Basal plate with three very large {1147}simple collar-holes. The
apical horn and the three feet are three-sided prismatic, smooth, about
twice as long as the columella, straight and widely divergent.

_Dimensions._--Shell 0.08 long, 0.1 broad.

_Habitat._--Tropical Pacific, Station 225, depth 4475 fathoms.


3. _Euscenium hemisphæricum_, n. sp.

Shell hemispherical smooth, half as long as broad, with small and numerous
subregular circular pores. Basal plate with three large triangular simple
collar-holes. Horn slender, three-sided prismatic, twice as long as the
columella. Feet very slender, with three denticulate edges, widely
divergent and curved like the quadrant of a circle.

_Dimensions._--Shell 0.04 long, 0.06 broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


4. _Euscenium tricolpium_, n. sp. (Pl. 53, fig. 12).

  _Archiscenium tricolpium_, Haeckel, 1881, Prodromus et Atlas, _loc. cit._

Shell cap-shaped, nearly hemispherical, with three vaulted hemispherical
bosoms between the three arches ascending from the feet to the horn.
Network very irregular, with polygonal meshes, of different form and size.
Basal plate with three large primary and some smaller irregular accessory
collar-holes. Horn slender, straight, twice as long as the columella. Feet
of the same length, slender, widely divergent, slightly curved. The three
edges of the horn and the feet are elegantly denticulated.

_Dimensions._--Shell 0.04 long, 0.08 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


5. _Euscenium tripospyris_, n. sp. (Pl. 84, fig. 8).

  _Tripospyris euscenium_, Haeckel, 1881, Prodromus et Atlas.

Shell nearly spherical, smooth, with numerous small circular pores. Basal
plate also with numerous small pores. Horn and feet stout, three-sided
prismatic, straight or slightly curved, about as long as the thin, somewhat
curved columella.  This species is closely allied to Tripospyris.

_Dimensions._--Shell 0.11 to 0.12 diameter, horn and feet 0.08 to 0.1 long.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.



Subgenus 2. _Euscenidium_, Haeckel.

_Definition._--Feet forked or branched.


6. _Euscenium furcatum_, n. sp.

Shell campanulate, smooth, with numerous irregular roundish pores. Basal
plate with nine pores (three larger central and six smaller distal). Horn
club-shaped, half as long as the columella. {1148}Feet twice as long,
cylindrical, parallel, vertical, forked at the distal end. (Similar to
_Tripospyris semantis_, Pl. 84, fig. 2, but without sagittal feet.)

_Dimensions._--Shell 0.07 long, 0.06 broad; horn 0.04 long, feet 0.1 long.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


7. _Euscenium quadratum_, n. sp.

Shell campanulate, smooth with subregular square pores. Basal plate with
three large pores. Horn and feet of the same size and shape, twice as long
as the columella, three-sided prismatic, each with four or five verticils
of lateral branches. (Similar to the cephalis of _Clathrocorys murrayi_,
Pl. 64, fig. 8, but with four free spines without connecting
lattice-wings.)

_Dimensions._--Shell 0.06 long, 0.05 broad; horn and feet 0.12 long.

_Habitat._--Central Pacific, Station 272, surface.


8. _Euscenium ramosum_, n. sp.

Shell subspherical, rough, with small subregular circular pores. Basal
plate with nine pores (three larger central and six smaller distal pores).
Horn and feet of the same size and form, three to four times as long as the
columella, three-sided prismatic, irregularly branched.

_Dimensions._--Shell 0.06 diameter, horn and feet 0.15 to 0.2 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 505. _Cladoscenium_,[122] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiperida# (vel Monocyrtida triradiata clausa) with a
free branched internal columella, prolonged into an apical horn. Three
basal feet free, without lateral wings.

The genus _Cladoscenium_ differs from the preceding _Euscenium_ only in the
ramification of the internal columella, which bears one or more verticils
of three ascending lateral branches. The three branches of each verticil
lie in the same equidistant meridian planes as the three basal feet, and
are inserted with their distal ends on the inner surface of the simple
lattice-shell. The three feet are also branched, but without vertical
lattice-wings. _Cladoscenium_ is perhaps closely allied to _Clathrocorys_.


1. _Cladoscenium fulcratum_, n. sp.

Shell subspherical, smooth, with large irregular roundish pores. Basal
plate with three large pores. Columella with a single verticil of three
ascending lateral branches. Apical horn as long as the {1149}columella,
simple, three-sided prismatic. Feet twice as long, widely divergent,
straight, prismatic, with some irregular basal branches.

_Dimensions._--Shell 0.06 diameter, horn 0.05 long, feet 0.1 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Cladoscenium ancoratum_, n. sp. (Pl. 53, fig. 13).

Shell campanulate, smooth, with irregular polygonal pores. Basal plate with
six pores (two large cardinal, two smaller jugular and two still smaller
cervical pores). Columella with a single verticil of three ascending
lateral branches (by mistake not distinct in the figure). Apical horn and
the three feet of the same form and size, slender, prismatic, twice to
three times as long as the shell, straight, in the distal half with three
slender recurved branches, anchor-shaped.

_Dimensions._--Shell 0.05 long, 0.04 broad; horn and feet 0.1 to 0.15 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


3. _Cladoscenium gladiatum_, n. sp.

Shell subspherical, with irregular polygonal pores. Basal plate with three
large pores. Columella with two verticils of three ascending lateral
branches. Apical horn as long as the columella, three-sided prismatic. Feet
of the same form, twice as long, in the distal half with two opposite
transverse branches, sword-shaped.

_Dimensions._--Shell 0.05 long, 0.06 broad; horn 0.04 long, feet 0.1 long.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


4. _Cladoscenium pinnatum_, n. sp.

Shell campanulate, with irregular polygonal pores. Basal plate with four
pores (two major cardinal and two minor jugular). Columella with two
verticils of three ascending lateral branches, and prolonged into a slender
prismatic apical horn of twice the length, which bears four such verticils.
Feet twice as long as the horn, pinnate, each with four or five pairs of
opposite lateral branches, decreasing towards the thin distal end.

_Dimensions._--Shell 0.06 long, 0.05 broad; horn 0.1 long, feet 0.2 long.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


5. _Cladoscenium verticillatum_, n. sp.

Shell campanulate, with subregular square pores. Basal plate with nine
pores (three larger central and six smaller distal). Columella with three
verticils of three ascending lateral branches. Apical horn and the three
basal feet of equal size and similar form, four to six times as long as the
columella, three-sided prismatic, each with four to five verticils of three
lateral branches, which are {1150}irregularly ramified and tapering towards
the distal end. (Similar to _Clathrocorys teuscheri_, Pl. 64, fig. 10, but
with four free spines, without connecting lattice-wings.)

_Dimensions._--Shell 0.07 long, 0.06 broad; horn and feet 0.2 to 0.25 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


6. _Cladoscenium pectinatum_, n. sp. (Pl. 98, fig. 2).

Shell subspherical, with irregular roundish pores. Basal plate with three
large holes. Columella with two verticils of three ascending lateral
branches. Apical horn and the three feet of nearly the same size and form,
three to four times as long as the columella, straight, three-sided
prismatic, each with five to eight verticils of three simple lateral
branches, tapering towards the distal end.

_Dimensions._--Shell 0.07 long, 0.08 broad; horn and feet 0.16 to 0.22
long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.



Genus 506. _Archiscenium_,[123] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiperida# (vel Monocyrtida triradiata clausa) with a
free simple internal columella, prolonged into an apical horn. Three basal
feet connected with the horn by three vertical lateral wings.

The genus _Archiscenium_ and the following nearly allied _Pteroscenium_ are
derived from the two preceding genera, from which they differ in the
development of three free vertical lateral lattice-wings; these arise from
the upper edge of the three basal feet and connect them with the three
edges of the apical horn. The basal part of the latter, enclosed in the
shell, forms an internal free columella, which in _Archiscenium_ is simple,
not branched.


1. _Archiscenium quadrispinum_, n. sp. (Pl. 53, fig. 11).

Shell hemispherical, smooth, with a small number of large irregular
polygonal meshes and thin bars. Basal lattice with three very large central
meshes and six smaller peripheral meshes (two on the base of each foot).
Apical horn and the three feet of equal size and similar form, slender,
pyramidal, widely divergent, straight, as long as the shell-diameter. Three
lateral wings small, little prominent, each with two or three irregular
meshes. Central capsule subspherical.

_Dimensions._--Shell 0.05 long, 0.1 broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


2. _Archiscenium clathrocorys_, n. sp.

Shell campanulate, smooth, with numerous irregular square meshes. Basal
lattice with three very large meshes. Apical horn and the three feet of
equal size and similar form, three-sided prismatic, {1151}widely divergent,
straight, twice as long as the shell-diameter. Three lateral wings broad,
each with a basal row of few very large irregular roundish meshes, and
several distal rows of small square meshes. This species is very similar to
_Clathrocorys murrayi_ (Pl. 64, fig. 8), but has no trace of thorax-wall.
The latter species may be derived from the former by development of the
thoracic lattice, which connects the three free feet.

_Dimensions._--Shell 0.05 long, 0.06 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Archiscenium tripterygium_, n. sp.

Shell hemispherical, smooth, with numerous irregular roundish meshes of
very different sizes. Basal lattice with four large meshes, two major
cardinal and two minor cardinal pores. Apical horn and the three feet of
similar form and size, slender prismatic, three to four times as long as
the shell; the horn straight, the feet curved. Three lateral wings very
delicate, with a basal row of few large irregular polygonal meshes, and
several distal rows of similar small pores.

_Dimensions._--Shell 0.04 long, 0.05 broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


4. _Archiscenium cyclopterum_, n. sp. (Pl. 98, fig. 3).

Shell hemispherical, with small irregular roundish pores. Basal lattice
with four large meshes, two major cardinal and two minor jugular pores.
Apical horn and the three feet of similar form and size, slender prismatic,
straight, twice to four times as long as the shell. Three lateral wings
nearly semicircular, densely latticed, with the same pores as the shell,
and smooth convex margin.

_Dimensions._--Shell 0.05 long, 0.06 broad.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


5. _Archiscenium callimitra_, n. sp.

Shell campanulate, with irregular polygonal pores. Basal lattice with nine
meshes (three larger central and six smaller distal pores, as in
_Callimitra carolotæ_, Pl. 63, fig. 8). Apical horn straight, prismatic,
slender, conical, twice as long as the shell. Feet longer and more slender,
slightly curved. Three lateral wings very broad, densely fenestrated, with
irregular polygonal pores of the same shape as in the similar _Callimitra
carolotæ_ (Pl. 63, fig. 1).

_Dimensions._--Shell 0.05 long, 0.04 broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



Genus 507. _Pteroscenium_,[124] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiperida# (vel Monocyrtida triradiata clausa) with a
free branched internal columella, prolonged into an apical horn. Three
basal feet connected with the horn by three vertical lateral wings.

{1152}The genus _Pteroscenium_ differs from the preceding _Archiscenium_
only in the ramification of the internal columella, and therefore exhibits
to it the same relation that _Cladoscenium_ bears to _Euscenium_. The
branches of the columella form also here verticils of ascending branches,
three in each verticil, and their distal ends are inserted on the inner
surface of the lattice-shell.


1. _Pteroscenium arcuatum_, n. sp. (Pl. 98, fig. 4).

Shell campanulate, smooth, nearly conical, somewhat broader than long, with
irregular dense network of small circular pores. Columella straight, with
two or three triradiate verticils of horizontal lateral branches, which are
inserted in the shell-wall. Horn slender pyramidal, as long as the shell.
Three divergent feet twice as long as the horn, strongly curved, thorny,
three-edged; the distance of their pointed ends twice as broad as the
shell. From the outer edge of each foot arise numerous ascending bristles,
which are connected together and with similar lateral branches of the horn
by curved arches, forming three delicate spiny vertical wings.

_Dimensions._--Shell 0.06 long, 0.08 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Pteroscenium arcadophorum_, n. sp.

Shell campanulate, smooth, with irregular polygonal pores, very similar to
the preceding species but with much broader wings, forming several arcades
with three to five rows of irregular meshes. Columella with five or six
triradiate verticils of lateral branches. Horn twice as long as the shell,
of the same length as the strongly curved spinulate feet.

_Dimensions._--Shell 0.09 long, 0.11 broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


3. _Pteroscenium pinnatum_, n. sp. (Pl. 53, figs. 14, 15, 16).

Shell campanulate, smooth, somewhat longer than broad, with irregular
delicate network of small roundish pores. Columella straight, with numerous
(eight to twelve) triradiate verticils of ascending lateral branches, which
are inserted in the shell-wall. The uppermost end of the columella is a
conical apical horn. The three divergent feet are smooth, slender, conical,
slightly curved, about as long as the shell, pinnate, with six to ten pairs
of ascending lateral branches, parallel to those of the columella and
inserted on the three vaulted lateral wings. (Fig. 14 exhibits the outside
of the shell, fig. 15 the internal structure of the cortina, fig. 16 the
basal view.)

_Dimensions._--Shell 0.1 long, 0.12 broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


4. _Pteroscenium spinulosum_, n. sp.

Shell campanulate, spinulate, about as long as broad, with small and
numerous irregular polygonal pores, very similar to the preceding species,
but differing in the more slender form of {1153}the horn and the feet,
bearing more numerous lateral branches (twelve to sixteen pairs on each
foot). Columella with six to eight triradiate verticils. Horn about as long
as the shell.

_Dimensions._--Shell 0.1 long, 0.1 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


5. _Pteroscenium macropodium_, n. sp.

Shell campanulate, spinulate, with irregular polygonal pores; very similar
to the two preceding species, but differing in the size and shape of the
three feet, which are for the most part solid, triangular, nearly parallel,
vertical, very slender, three times as long as the shell, latticed only at
the curved base, with few pairs of lateral branches. Columella with four to
six triradiate verticils, as long as the stout triangular pyramidal horn.

_Dimensions._--Shell 0.1 long, 0.08 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


6. _Pteroscenium tripocolpum_, n. sp.

Shell campanulate, spinulate, similar to _Euscenium tricolpium_ (Pl. 53,
fig. 12) with three vaulted hemispherical bosoms between the three delicate
arachnoidal vertical wings. Network loose, very irregular, with polygonal
meshes of very different sizes. Columella with three or four triradiate
verticils, as long as the slender pyramidal horn. Three feet twice as long,
somewhat curved, widely divergent, with three or four pairs of lateral
branches. The three edges of the feet and of the horn are elegantly
denticulated.

_Dimensions._--Shell 0.06 long, 0.09 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



Genus 508. _Peridium_,[125] Haeckel, 1881, p. 429.

_Definition._--#Archiperida# (vel Monocyrtida triradiata clausa) without
internal columella, with an apical horn.

The genus _Peridium_ (or _Archiperidium_, Prodromus, _loc. cit._) and the
two following nearly allied genera form together the small group of
Archibursida, differing from the four preceding genera (the Euscenida) in
the absence of an internal free columella. The three basal feet have
therefore no direct connection with the apical horn. _Peridium_, the
ancestral form of the Archibursida, may have originated either from
_Euscenium_ by reduction and loss of the columella, or directly from
_Tripospyris_ by loss of the sagittal ring and the longitudinal
constriction.



Subgenus 1. _Peridarium_, Haeckel.

_Definition._--Feet smooth, simple, neither spiny nor branched.


{1154}1. _Peridium lasanum_, n. sp.

Shell subspherical, smooth, with subregular circular pores. Basal plate
with three large meshes. Horn apical, vertical, of the same size and form
as the three divergent smooth feet, slender pyramidal, twice to three times
as long as the shell.

_Dimensions._--Shell-diameter 0.06 to 0.07, length of the three spines 0.15
to 0.2.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.


2. _Peridium papillatum_, n. sp.

Shell subspherical, papillate, with subregular circular pores. Basal plate
with four meshes (two major cardinal and two minor jugular pores). Horn
occipital, oblique, three-sided pyramidal, half as long as the shell and as
the three widely divergent, subhorizontal, smooth feet.

_Dimensions._--Shell diameter 0.07 to 0.08, length of the horn 0.04, of the
feet 0.08.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Peridium curvipes_, n. sp.

Shell hemispherical, thorny, with irregular roundish pores. Basal plate
with six pores (two larger middle cardinal, two smaller anterior jugular
and two smaller posterior cervical pores, as in Pl. 53, figs. 13, 18). Horn
conical, oblique, arising from the middle of the occipital face, half as
long as the shell. Feet slender, conical, curved, smooth, twice as long as
the shell.

_Dimensions._--Shell 0.04 long, 0.06 broad; horn 0.02 long; feet 0.08 long.

_Habitat._--Tropical Pacific, Station 206, depth 2100 fathoms.



Subgenus 2. _Archiperidium_, Haeckel.

_Definition._--Feet spiny or branched.


4. _Peridium spinipes_, n. sp. (Pl. 53, fig. 9).

Shell ovate, rough or thorny, with irregular roundish pores. Basal plate
with four pores (two larger cardinal and two smaller jugular pores). Horn
oblique, occipital, three-sided pyramidal, half as long as the shell,
connected with the caudal foot by a prominent crest. Three feet
horizontally expanded, prismatic, spiny, about as long as the shell.

_Dimensions._--Shell 0.08 long, 0.06 broad; horn 0.04 long, feet 0.06 to
0.09 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


5. _Peridium palmipes_, n. sp. (Pl. 53, fig. 10).

Shell ovate, smooth, with irregular roundish pores. Basal plate with three
large pores. Horn oblique, three-sided pyramidal, about as long as the
shell, inserted near its occipital base. Three feet prismatic, slender,
half as long, ending with a broad dentate plate.

_Dimensions._--Shell 0.06 long, 0.05 broad; horn 0.05 long, feet 0.03 long.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.


{1155}6. _Peridium alatum_, n. sp. (Pl. 97, fig. 7).

Shell subspherical smooth, with regular circular, hexagonally-framed pores.
Basal plate with nine pores (three larger central and six smaller distal
pores). Horn apical, of equal size and the same form as the three feet,
three-sided prismatic, with three broad prominent wings, somewhat longer
than the shell.

_Dimensions._--Shell 0.07 long, 0.08 broad; horn and feet 0.1 to 0.12 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


7. _Peridium cervinum_, n. sp.

Shell subspherical, spiny, with subregular circular pores. Basal plate with
four pores (?). Horn apical, conical, about as long as the shell. Feet
three to four times as long, cylindrical curved, with irregular simple or
forked branches like the antlers of a deer.

_Dimensions._--Shell diameter 0.1, horn 0.1 long, feet 0.3 to 0.4 long.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



Genus 509. _Archipera_,[126] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiperida# (vel Monocyrtida triradiata clausa) without
internal columella, with two or more apical horns.

The genus _Archipera_ differs from the preceding _Peridium_ only in the
multiplication of the apical horn, which in the latter is always simple.
The number of horns is usually two or three, sometimes four or more. The
species bearing three horns may be derived directly from _Triceraspyris_ by
loss of the sagittal ring.


1. _Archipera cortiniscus_, n. sp. (Pl. 98, fig. 5).

Shell ovate, thorny, with large roundish pores, which are closed by
sieve-plates with numerous small porules. Basal plate with two pairs of
simple large pores (two smaller jugular and two larger cardinal, similar to
Pl. 98, fig. 10_b_). Two horns divergent, curved, slender, pyramidal; the
apical horn longer than the shell, the frontal horn shorter. Three feet
divergent, longer than the shell, three-sided prismatic, at the distal end
club-shaped, thorny.

_Dimensions._--Shell 0.1 long, 0.08 broad; horns and feet 0.11 to 0.14
long.

_Habitat._--Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Archipera pentacantha_, n. sp.

Shell pear-shaped, smooth, with numerous and small irregular roundish
pores. Basal plate with three larger pores. Two horns and three feet of
nearly equal size and similar form, three-sided {1156}prismatic, about as
long as the shell diameter, somewhat curved. The apical horn stands on the
apex, the frontal horn half-way up the shell.

_Dimensions._--Shell 0.08 long, 0.06 broad; horns and feet 0.05 to 0.07
long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


3. _Archipera bicornis_, n. sp.

Shell ovate, rough, with small regular circular, sparsely scattered pores.
Basal plate with four larger central and a peripheral coronal of twelve
smaller pores. Two horns near the apex widely divergent, somewhat shorter
than the shell, of equal size and similar form. Three feet twice as long,
horizontally expanded. All five spines slender, three-sided pyramidal,
straight.

_Dimensions._--Shell 0.07 long, 0.06 broad; horns 0.05 long, feet 0.1 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


4. _Archipera tricornis_, n. sp.

Shell subspherical, smooth, with subregular circular pores. Basal plate
with four large meshes (two major cardinal and two minor jugular pores). On
the apex three divergent pyramidal horns of different size, one larger
occipital and two smaller frontal horns. Three feet prismatic, about twice
as long as the shell.

_Dimensions._--Shell diameter 0.05, length of the feet 0.1.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.


5. _Archipera quadricornis_, n. sp.

Shell ovate, smooth, with a small number of irregular roundish, widely
scattered pores. Basal plate with four crossed meshes of nearly equal size.
On the equator there arise four divergent prismatic horns of nearly equal
size, three of which correspond to the three feet, whilst the fourth is
opposite to the caudal foot. The three feet are also prismatic, as long as
the shell, horizontally expanded. (Similar to the upper half of
_Lithomelissa decacantha_, Pl. 56, fig. 2, but without thorax.)

_Dimensions._--Shell 0.05 long, 0.04 broad; horns and feet 0.06 long.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


6. _Archipera multicornis_, n. sp.

Shell hemispherical, spiny, with irregular polygonal pores. Basal plate
with six meshes (?). Between the smaller spines of the surface arise six
larger conical divergent horns. Three feet also conical, divergent, about
twice as long as the shell and the horns.

_Dimensions._--Shell 0.05 long, 0.07 broad; horns 0.05 long, feet 0.1 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



{1157}Genus 510. _Archibursa_,[127] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiperida# (vel Monocyrtida triradiata clausa) without
internal columella and without apical horn.

The genus _Archibursa_ has probably arisen from _Peridium_ by loss of the
apical horn, and is the only genus of Archiperida which bears no horn. The
three basal feet are well-developed. It differs from the similar
_Tristylospyris_ by the absence of the sagittal ring and the corresponding
longitudinal constriction.


1. _Archibursa tripodiscus_, n. sp. (Pl. 98, fig. 6).

Shell subspherical, smooth, with irregular roundish pores. Basal plate with
three large triangular pores of equal size (fig. 6). Three feet widely
divergent, straight, three-sided prismatic, about as long as the diameter
of the shell.

_Dimensions._--Diameter of the shell 0.07, length of the feet 0.09.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Family LX. #PHÆNOCALPIDA#, n. fam.

  _Archiphormida_ et _Archiphænida_, Haeckel, 1881, Prodromus, pp. 428,
      429.

_Definition._--#Monocyrtida# multiradiata. (#Cyrtoidea# with a simple, not
jointed shell, resembling a simple cephalis, with numerous radial apophyses
(four to nine or more).

The family #Phænocalpida#, composed of the Archiphormida and Archiphænida
of my Prodromus, comprises those #Cyrtoidea# in which the lattice-shell is
quite without transverse constriction, but bears numerous radial apophyses.
The two subfamilies differ in the shape of the basal mouth, which in the
Archiphormida is a simple wide opening, but is closed in the Archiphænida
by a lattice-plate.

Several Phænocalpida were formerly described by Ehrenberg, viz.,
_Halicalyptra virginica_ (in 1844) and _Litharachnium arachnodiscus_ (in
1872, called by him _Carpocanium_, though it is quite different from this
genus, and closely allied to my _Litharachnium tentorium_, figured in
1862). These forms belong to the Archiphormida (with open mouth). Several
fossil Archiphænida (with closed mouth) were figured by Ehrenberg, in 1875,
as belonging to _Petalospyris_ (_ocellata_, _carinata_, _flabellum_),
though the absence of the sagittal ring and the corresponding longitudinal
constriction demonstrates their character as _Phænocalpis_.

{1158}The Phænocalpida are probably an artificial family, composed of three
or four (or perhaps more) different groups, which have a quite different
origin. The Litharachnida (genera 511-515) and the Haliphormida (genera
516-518) are probably derived from the Sethophormida by loss of the
cephalis, the retrograde metamorphosis of which may be observed in all its
different stages. The Halicalyptrida (genera 519-521) are perhaps
independent of the other Phænocalpida, and may be Archicorida which have
produced a corona of teeth around the mouth, without relation to lost
radial ribs. The Phænoscenida (_Phænocalpis_, _Phænoscenium_) may be
derived from the Euscenida (genera 504-507) by interpolation of interradial
feet between the three primary ones, or directly from the #Plectoidea#. The
Calpophænida, on the other hand (_Calpophæna_, _Archiphæna_), may have
arisen from the Zygospyrida (_Petalospyris_, _Gorgospyris_) by loss of the
sagittal ring and the longitudinal constriction. The phylogeny of the
Phænocalpida is therefore a very complicated problem, as yet unsolved.

_Synopsis of the Genera of Phænocalpida._

  -------------------------------------------------------------------------
  I. Subfamily Archiphormida.
     Basal mouth of the shell a simple wide opening.
                            --------------------
     Radial ribs enclosed in the wall of the shell, usually prolonged into
        free terminal feet.
  -------------------------------------------------------------------------
                      { Shell simple, with simple
                      {   network,                   511. _Bathropyramis_.
  Shell slender,      {
   pyramidal          { Shell simple, with double
   (without horn).    {   network,                   512. _Cinclopyramis_.
                      {
                      { Shell double, with an outer
                      {   mantle,                    513. _Peripyramis_.

  Shell flatly        } Radial ribs simple,          514. _Litharachnium_.
   campanulate or     }
   discoidal (without } Radial ribs branched,        515. _Cladarachnium_.
   horn).             }

                      { Mouth smooth, constricted
  Shell ovate,        {   (no horn),                 516. _Cystophormis_.
   urceolate or       {
   campanulate.       { Mouth, with    { With horn,  517. _Haliphormis_.
                      { a corona of    {
                      {   feet.        { No horn,    518. _Archiphormis_.
  -------------------------------------------------------------------------
  No radial ribs in the wall of the shell. Mouth surrounded by a corona of
     free terminal feet.
  -------------------------------------------------------------------------
                                       { With horn,  519. _Halicalyptra_.
  Shell simple without mantle.         {
                                       { No horn,    520. _Carpocanistrum_.

  Shell double, with an external mantle (no horn),   521. _Arachnocalpis_.
  -------------------------------------------------------------------------
  II. Subfamily Archiphænida. Basal mouth closed by a lattice-plate.
                            --------------------
      In the axis of the shell-cavity a free columella.
  -------------------------------------------------------------------------
  In the axis of the     { Columella simple,         522. _Phænocalpis_.
   shell-cavity a        {
   free columella.       { Columella branched,       523. _Phænoscenium_.
  -------------------------------------------------------------------------
  Shell-cavity simple, without axial columella.
  -------------------------------------------------------------------------
  Shell-cavity simple,   { Apex with a horn,         524. _Calpophæna_.
   without axial         {
   columella.            { No apical horn,           525. _Archiphæna_.



{1159}Subfamily 1. ARCHIPHORMIDA, Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Phænocalpida# with the basal mouth of the shell open (vel
Monocyrtida multiradiata aperta).



Genus 511. _Bathropyramis_,[128] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
simple, slender pyramidal shell and numerous radial beams (six to nine or
more). Network simple, with large, unfenestrated, quadrangular meshes.

The genus _Bathropyramis_ and the following four nearly allied genera form
together a peculiar group of Archiphormida, the Litharachnida, possessing
near relations to _Sethopyramis_ and the allied Sethophormida, from which
they are probably derived by reduction and loss of the small cephalis. The
shell in all these forms is distinctly pyramidal, composed of numerous
divergent radial beams (commonly six to nine), which form the edges of the
pyramid, and are connected by parallel horizontal rings. The quadrangular
meshes so produced are quite simple in _Bathropyramis_. This genus cannot
be sharply separated from _Sethopyramis_, its ancestral form.



Subgenus 1. _Acropyramis_, Haeckel, 1881, Prodromus, p. 428.

_Definition_.--Shell smooth, without spines on the surface.


1. _Bathropyramis acephala_, n. sp.

Shell smooth, slenderly pyramidal, with three cortinar pores at the apex
and with six stout radial beams or longitudinal ribs, connected by twelve
to sixteen complete hexagonal horizontal rings. Meshes nearly square,
increasing gradually in size towards the mouth.

_Dimensions._--Shell 0.25 long, 0.15 broad.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


2. _Bathropyramis quadrata_, n. sp. (Pl. 54, fig. 1).

Shell smooth, slenderly pyramidal, with three cortinar pores at the apex
and nine stout radial beams, connected by eight to twelve complete circular
horizontal rings. Meshes subregular, square, increasing in size gradually
towards the circular mouth.

_Dimensions._--Shell 0.2 to 0.3 long, 0.12 to 0.2 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


{1160}3. _Bathropyramis trapezoides_, n. sp. (Pl. 54, fig. 3).

Shell smooth, broadly pyramidal, with four cortinar pores at the apex and
eight (or sometimes nine) stout radial beams, connected by twelve to
sixteen complete octagonal horizontal rings. Meshes trapezoidal, of nearly
equal length, but gradually increasing in breadth.

_Dimensions._--Shell 0.3 long, 0.3 broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


4. _Bathropyramis interrupta_, n. sp. (Pl. 55, fig. 7).

Shell smooth, flatly pyramidal, nearly discoidal, with four cortinar pores
at the apex and nine to ten stout radial beams, connected by eight to
sixteen interrupted rings; the rings are complete only in the apical part,
in the distal part more or less irregularly interrupted.

_Dimensions._--Shell 0.12 long, 0.36 broad.

_Habitat._--North Atlantic, Station 354, surface.


5. _Bathropyramis medusa_, n. sp.

Shell smooth, flatly pyramidal, nearly discoidal, with four cortinar pores
and numerous radial beams (thirty to fifty); the four perradial of these
are prolongations of the four cortinar beams, and alternate with four
interradial of the same size. Between these are intercalated eight adradial
beams arising from the third ring; and between the former and the latter,
sixteen to twenty-four peripheral radial beams, arising from the fourth to
the sixth ring. The inner four to six rings are complete, the outer ten to
fifteen irregularly interrupted.

_Dimensions._--Shell 0.08 long, 0.3 to 0.4 broad.

_Habitat._--South Atlantic, Station 338, surface.



Subgenus 2. _Cladopyramis_, Haeckel, 1881, Prodromus, p. 428.

_Definition_.--Shell spiny, with prominent simple or branched spines on the
surface.


6. _Bathropyramis spinosa_, n. sp.

Shell spiny, slenderly pyramidal, with three cortinar pores at the apex and
with nine strong radial beams, connected by fifteen to twenty complete
parallel rings. Meshes subregular square, increasing gradually in size.
Surface covered with simple, strong conical spines, arising from the nodal
points.

_Dimensions._--Shell 0.24 long, 0.16 broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


{1161}7. _Bathropyramis ramosa_, n. sp. (Pl. 54, fig. 4).

Shell spiny, slenderly pyramidal, with three cortinar pores at the apex,
and with nine (or sometimes eight or ten) strong radial beams, connected by
fifteen to eighteen complete parallel rings. Meshes subregular, square,
increasing gradually in size. Surface covered with forked or irregularly
branched spines, arising from the nodal points.

_Dimensions._--Shell 0.3 long, 0.17 broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.



Genus 512. _Cinclopyramis_,[129] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
simple, slender, pyramidal shell, and numerous radial beams (six to nine or
more). Network double, with a delicate arachnoidal fenestration, filling up
the large quadrangular meshes.

The genus _Cinclopyramis_ differs from the preceding _Bathropyramis_ in the
development of a very delicate secondary network, filling up the large
quadrangular meshes, which are produced by the crossing of the radial beams
and the parallel horizontal rings. It therefore bears the same relation to
the preceding genus that _Plectopyramis_ does to _Sethopyramis_; it is
perhaps derived directly from the former by loss of the small cephalis.


1. _Cinclopyramis cribellum_, n. sp.

  _Cinclopyramis cribellum_ = "Ladder of lattice-shape," Bury, 1862,
  Polycystins of Barbados, pl. xii. fig. 6.

Shell slender, pyramidal, with six strong radial ribs, which are connected
by twelve to sixteen complete horizontal rings. Meshes trapezoidal, filled
up by a very delicate and regular secondary network with square porules
(two to four horizontal threads in each larger mesh).

_Dimensions._--Shell 0.2 to 0.3 long, 0.12 to 0.16 broad.

_Habitat._--Fossil in Barbados.


2. _Cinclopyramis infundibulum_, n. sp. (Pl. 54, fig. 7).

Shell slender, pyramidal, with nine strong radial ribs, which are connected
by eighteen to twenty-four complete horizontal rings. Meshes subregular
square, filled up by a very delicate and regular secondary network with
square porules (ten to twelve horizontal threads in each larger mesh). Apex
of the pyramid with three very small cortinar pores.

_Dimensions._--Shell 0.3 to 0.4 long, 0.2 to 0.25 broad.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.


{1162}3. _Cinclopyramis lithosestrum_, n. sp.

Shell slender, pyramidal, with twelve strong radial ribs (six primary
longer and six secondary shorter) connected by twelve to fifteen
interrupted irregular rings. Meshes irregular square or trapezoidal, filled
up by a delicate secondary network with irregular polygonal porules.

_Dimensions._--Shell 0.4 to 0.5 long, 0.2 to 0.3 broad.

_Habitat._--Fossil in Barbados.



Genus 513. _Peripyramis_,[130] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
double, slenderly pyramidal shell, and numerous radial beams (six to nine
or more). Network double, with an external arachnoidal or spongy envelope
around the primary lattice-shell.

The genus _Peripyramis_ differs from its probable ancestral form,
_Bathropyramis_, by development of a delicate external envelope around the
primary shell, and therefore bears to it the same relation that
_Spongopyramis_ among the Dicyrtida does to _Sethopyramis_. It may also be
derived directly from the former by loss of the cephalis.


1. _Peripyramis circumtexta_, n. sp. (Pl. 54, fig. 5).

Shell slender, pyramidal, with nine strong radial beams, connected by
fifteen to twenty transverse horizontal rings, which are partly complete,
partly interrupted. Meshes subregular, square. From the nodal points of the
surface there arise branched spines, which at equal distances from it are
connected by thin threads, forming a delicate outer arachnoidal shell with
large irregular polygonal meshes.

_Dimensions._--Shell 0.32 long, 0.16 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Peripyramis spongiosa_, n. sp.

Shell slender, pyramidal, with nine strong radial beams, connected by
twelve to eighteen irregular interrupted rings. Meshes irregular, square or
polygonal. From the whole surface arise numerous branched spines, which by
communication and dense ramification form an outer spongy envelope around
the shell. (Similar to _Spongopyramis spongiosa_, Pl. 56, fig. 10.)

_Dimensions._--Shell 0.45 long, 0.32 broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



{1163}Genus 514. _Litharachnium_,[131] Haeckel, 1860, Monatsber. d. k.
preuss. Akad. d. Wiss. Berlin, p. 835.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
flatly conical, tent-shaped or nearly discoidal shell, and numerous,
simple, radial beams in its wall.

The genus _Litharachnium_, and the closely allied genus _Cladarachnium_,
differ from the preceding similar genera mainly in the flat form of the
depressed shell, which is not slenderly pyramidal, but more tent-shaped or
nearly discoidal. The radial ribs are generally not straight, but more or
less curved. The top of the tent exhibits three or four important meshes,
the original pores of the cortinar septum. _Litharachnium_ may be derived
directly from _Sethophormis_ by reduction and loss of the cephalis.



Subgenus 1. _Litharachnidium_, Haeckel.

_Definition._--Apex with three cortinar pores (one odd sternal and two
paired cardinal pores).


1. _Litharachnium tentorium_, Haeckel.

  Litharachnium tentorium, Haeckel, 1862, Monogr. d. Radiol., p. 281, Taf.
  iv. figs. 7-10.

Shell flatly conical or tent-shaped, with concave lateral outlines. Apex
with three equal cortinar pores. Twenty radial ribs at nearly equal
distances. Between them very numerous and thin secondary ribs, crossed by
more than one hundred concentric rings. Pores square, as in all the
following species. Margin truncate, circular.

_Dimensions._--Shell 0.35 long, 0.8 broad.

_Habitat._--Mediterranean (Messina).


2. _Litharachnium araneosum_ (Pl. 55, figs. 8, 10).

Shell flatly conical, nearly discoidal, with straight lateral outlines.
Apex with three unequal cortinar pores (one odd smaller sternal and two
paired larger cardinal pores). Twenty radial ribs at unequal distances,
with numerous intercalated secondary ribs. Margin ciliate.

_Dimensions._--Shell 0.18 long, 0.32 broad.

_Habitat._--Central Pacific, Station 271, surface.


{1164}3. _Litharachnium arachnodiscus_, Haeckel.

  _Litharachnium arachnodiscus_, Haeckel, 1862, Monogr. d. Radiol., p. 283.

  _Carpocanium arachnodiscus_, Ehrenberg, 1861, Monatsber. d. k. preuss.
  Akad. d. Wiss. Berlin, p. 296; Abhandl. d. k. Akad. d. Wiss. Berlin,
  1872, Taf. ii. fig. 8.

Shell flatly campanulate, nearly discoidal, with convex (?) lateral
outlines. Apex with three unequal cortinal pores. Nine stronger radial
primary ribs complete; between them numerous secondary intercalated ribs
(sixty to seventy). Margin ciliate.

_Dimensions._--Shell 0.03 long, 0.1 broad (?).

_Habitat._--Arctic Ocean (between Greenland and Iceland), depth 1000
fathoms (Schaffner).


4. _Litharachnium epeira_, n. sp. (Pl. 55, fig. 9).

Shell flatly conical or tent-shaped, with concave lateral outlines. Apex
with three unequal cortinar pores. Twelve stronger radial primary ribs
complete; between them numerous (twenty-four to thirty-six) thinner
secondary, and very numerous (more than one hundred) tertiary ribs. Margin
reflexed, like the curved brim of a hat.

_Dimensions._--Shell 0.12 long, 0.27 broad.

_Habitat._--Central Pacific, Station 274, surface.



Subgenus 2. _Litharachnoma_, Haeckel.

_Definition._--Apex with four cortinar pores (two anterior jugular and two
posterior cardinal pores).


5. _Litharachnium discoides_, n. sp.

Shell flat, funnel-shaped, nearly discoidal, with concave outlines. Apex
with four unequal cortinar pores (two smaller jugular and two larger
cardinal pores). Twelve strong primary or perradial ribs alternating with
twelve weaker secondary or interradial ribs; between these there are
twenty-four shorter tertiary or adradial ribs, and in the outer flat,
discoidal, half of the shell very numerous peripheral radial ribs (more
than two hundred to three hundred). Margin flat, discoidal.

_Dimensions._--Shell about 0.2 long, 1.12 broad.

_Habitat._--Equatorial Atlantic, Station 347, surface.


6. _Litharachnium pilidium_, n. sp.

Shell flat, hat-shaped, with S-shaped outlines, in the upper half convex,
in the lower half concave. Apex with four equal crossed cortinar pores.
Thirty primary ribs of equal size; four of them are the prolongations of
the four cortinar beams, eight intercalate between these secondary,
{1165}and the other eighteen tertiary. Between them very numerous
peripheral beams. Margin broad horizontal, reflexed like the brim of a
"Bismarck" hat.

_Dimensions._--Shell 0.17 long, 0.38 broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.



Genus 515. _Cladarachnium_,[132] Haeckel, 1881, Prodromus, p. 430.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
flatly conical, tent-shaped or nearly discoidal shell, and numerous
branched radial beams.

The genus _Cladarachnium_ differs from the preceding _Litharachnium_ only
in the ramification of the radial beams, the distal ends of which project
over the margin of the shell. Only one species of the genus has been
observed.


1. _Cladarachnium ramosum_, n. sp. (Pl. 55, figs. 5, 6).

Shell flatly conical or tent-shaped, with nearly straight lateral outlines;
apical part somewhat higher. Apex with three cortinar pores surrounded by a
few girdles of larger pores. From these there arise about twelve to fifteen
strong radial beams at unequal distances; these are somewhat curved and
irregularly branched. The network between them has irregular polygonal
meshes and is more delicate towards the periphery. Margin with twenty-four
to thirty irregular indentations or concave excisions, separated by the
prominent distal ends of the branched ribs.

_Dimensions._--Shell 0.16 long, 0.4 broad.

_Habitat._--Central Pacific, Station 271, surface.



Genus 516. _Cystophormis_,[133] n. gen.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
ovate or urceolate shell and numerous radial ribs in its wall. Mouth more
or less constricted, smooth, truncated. Apex without horn.

The genus _Cystophormis_, like the preceding genera, exhibits numerous
prominent radial or longitudinal ribs in the wall of the urceolate shell;
it differs from these in the constricted and truncated mouth, with smooth
margin of the peristome.


1. _Cystophormis pila_, n. sp. (Pl. 52, fig. 1).

Shell balloon-shaped, subspherical, with twenty denticulate meridional
ribs, alternating with twenty longitudinal rows of circular pores, which
are twice as broad as the bars. Peristome constricted and then dilated,
smooth, half as broad as the shell.

_Dimensions._--Shell 0.11 long, 0.09 broad; mouth 0.06 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


{1166}2. _Cystophormis ærostatica_, n. sp. (Pl. 52, figs. 2, 3).

Shell balloon-shaped, subspherical, with twenty smooth meridional ribs,
alternating with twenty longitudinal rows of circular pores, of the same
breadth as the bars. Peristome constricted, about half as broad as the
shell.

_Dimensions._--Shell 0.09 long, 0.07 broad; mouth 0.03 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


3. _Cystophormis spiralis_, n. sp. (Pl. 51, fig. 9).

Shell ovate, one and a half times as long as broad, with twenty spirally
convoluted, elegantly denticulated ribs, alternating with twenty spiral
rows of small circular pores, of about the same breadth as the bars.
Peristome constricted, very small, only one-seventh as broad as the shell.

_Dimensions._--Shell 0.1 long, 0.07 broad; mouth 0.01 broad.

_Habitat._--West Tropical Pacific, Station 225, depth 4475 fathoms.


4. _Cystophormis tabulata_ (Pl. 79, fig. 2).

Shell urceolate and tabulate, twice as long as broad with twenty-five to
thirty denticulated longitudinal ribs crossed by twenty to twenty-four
transverse rings. Pores therefore regularly disposed in longitudinal and
transverse rows; each pore circular, with a square frame. Peristome
constricted, scarcely half as broad as the shell.

_Dimensions._--Shell 0.2 long, 0.1 broad; mouth 0.04 broad.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms



Genus 517. _Haliphormis_,[134] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54 (_sensu mutato_).

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
numerous radial ribs in the wall of the campanulate shell, prolonged into
free terminal feet. Apex with a horn.

The genus _Haliphormis_ (with an apical horn) and the following
_Archiphormis_ (without a horn) comprise those Archiphormida in which the
open mouth is more or less constricted and surrounded by a coronet of
radial feet, as terminal prolongations of the radial ribs of its wall. The
few forms, upon which Ehrenberg originally founded the genus _Haliphormis_,
are partly not recognisable, partly belong to other genera. We therefore
give here a new definition of the genus, as stated in my Prodromus, 1881,
p. 428.


{1167}1. _Haliphormis lagena_, n. sp. (Pl. 97, fig. 5)

Shell bottle-shaped, twice as long as broad, tapering towards both ends,
with nine longitudinal curved ribs. These are connected by irregular
transverse beams, and the quadrangular meshes, so produced, are filled up
by irregular, delicate, arachnoidal framework. The constricted mouth is
half as broad as the middle part of the shell and surrounded by nine
slender convergent feet, the free distal ends of the ribs. The apex bears a
small knob with an oblique horn, perhaps the rudimentary cephalis of
_Sethamphora_ or _Sethopyramis_ (?).

_Dimensions._--Shell 0.6 to 0.7 long, 0.3 to 0.4 broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


2. _Haliphormis costata_, n. sp.

Shell campanulate, somewhat longer than broad, with twelve prominent
longitudinal ribs, alternating with twelve rows of regular circular pores.
Mouth constricted half as broad as the shell, with twelve long triangular
feet, formed by the free distal ends of the ribs. Apical horn short and
stout, triangular pyramidal.

_Dimensions._--Shell 0.12 long, 0.1 broad; mouth 0.07 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 518. _Archiphormis_,[135] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
numerous radial ribs in the wall of the campanulate or urceolate shell,
prolonged into free terminal feet. Apex without horn.

The genus _Archiphormis_ differs from the preceding _Haliphormis_, its
probable ancestral form, in the absence of the apical horn. The number of
the longitudinal ribs, which are prolonged into terminal feet, is from six
to nine or twelve or even more.


1. _Archiphormis cancellata_, Haeckel.

  (?) _Halicalyptra cancellata_, Ehrenberg, 1854, Monatsber. d. k. preuss.
  Akad. d. Wiss. Berlin, p. 243.

Shell cup-shaped or campanulate, with six prominent ribs, prolonged into
six terminal triangular feet, one-third as long as the shell. Ribs
connected by five or six transverse horizontal rings; meshes between them
rounded squarish.  (As Ehrenberg has given no figure of this species, its
identity with the Challenger specimen is doubtful.)

_Dimensions._--Shell 0.08 long, 0.06 broad; mouth 0.04 broad.

_Habitat._--North Atlantic, Station 353, depth 2965 fathoms.


{1168}2. _Archiphormis campanulata_, n. sp.

Shell campanulate, with nine prominent denticulate ribs, prolonged into
nine terminal feet, which are broad, lamellar, truncate, nearly vertical,
one-third as long as the shell. Pores between the ribs circular, disposed
in nine longitudinal and seven to eight transverse rows.

_Dimensions._--Shell 0.09 long, 0.1 broad; mouth 0.06 broad.

_Habitat._--Central Pacific, Station 270, depth 2925 fathoms.


3. _Archiphormis urceolata_, n. sp. (Pl. 98, fig. 11).

Shell urceolate, with nine smooth prominent curved ribs, prolonged into
nine triangular convergent short feet, scarcely one-sixth as long as the
shell. Pores between the ribs in nine regular longitudinal rows, twice or
three times as broad as long, quadrangular, eight to twelve pores in each
row. Mouth constricted, half as broad as the shell.

_Dimensions._--Shell 0.13 long, 0.11 broad; mouth 0.06 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



Genus 519. _Halicalyptra_,[136] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54 (_sensu emendato_).

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta)
without radial ribs in the wall of the campanulate or ovate shell. Mouth
with a coronet of radial feet. Apex with a horn.

The genus _Halicalyptra_ and the two following closely allied genera differ
from the preceding Archiphormida in the absence of radial ribs. The
multiradiate structure is indicated only by the terminal spines or feet,
forming a coronet around the mouth. These feet are either the free ends of
reduced ribs, or new productions of the peristome. _Halicalyptra_ may be
derived from _Calpophæna_ and _Petalospyris_ by loss of the basal
lattice-plate of the cephalis. But it is also possible that it has been
derived from _Anthocyrtis_ by loss of the cephalis, and that its shell
corresponds to the thorax of the latter.



Subgenus 1. _Acrocalpis_, Haeckel, 1881, Prodromus, p. 427.

_Definition._--Shell smooth, without spines or thorns (other than the feet
and the apical horn).


{1169}1. _Halicalyptra virginica_, Ehrenberg.

  _Halicalyptra virginica_, Ehrenberg, 1854, Mikrogeol., Taf. xviii. fig.
  110.

  _Halicalyptra virginica_, Haeckel, 1862, Monogr. d. Radiol., p. 289.

  _Haliomma virginicum_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.
  Wiss. Berlin, p. 71.

  _Acrocalpis virginica_, Haeckel, 1881, Prodromus, p. 427.

Shell smooth, campanulate, nearly hemispherical. Pores subregular circular,
about as broad as the bars. Horn conical, half as long as the shell.
Peristome scarcely constricted, with six conical divergent feet, as long as
the horn.

_Dimensions._--Shell diameter 0.04 to 0.05, length of the feet 0.02.

_Habitat._--Fossil in tertiary rocks of Barbados and North America
(Richmond, Virginia).


2. _Halicalyptra campanula_, n. sp.

  _Podocyrtis spinosa_, Bury, 1862, Polycystins of Barbados, pl. xvii. fig.
  3.

Shell smooth, campanulate. Pores irregular, roundish, about as broad as the
bars. Horn large conical, about as long as the shell. Peristome not
constricted, with six large divergent feet, which are as long as the shell,
lamellar, with dentate edges.

_Dimensions._--Shell diameter 0.07, length of the feet 0.07.

_Habitat._--Fossil in Barbados.


3. _Halicalyptra ampulla_, n. sp.

  _Petalospyris foveolata_, var., Bury, 1862, Polycystins of Barbados, pl.
  ix. fig. 1.

Shell smooth, subspherical, inflate. Pores regular, circular, twice as
broad as the bars. Horn slender conical, about as long as the shell.
Peristome constricted, with six divergent cylindrical, irregularly curved
feet, twice to three times as long as the shell.

_Dimensions._--Shell diameter 0.12, feet 0.2 to 0.3 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; also fossil
in Barbados.


4. _Halicalyptra novena_, n. sp.

Shell smooth, campanulate. Pores irregular, roundish. Horn slender conical,
about as long as the shell. Peristome slightly constricted, with nine
slender divergent feet of the same length. (Very similar to _Petalospyris
foveolata_, Ehrenberg, but without internal columella and ring, with
perfectly simple shell-cavity and open mouth.)

_Dimensions._--Shell 0.09 diameter, feet 0.1 long.

_Habitat._--Fossil in Barbados.


5. _Halicalyptra petalospyris_, n. sp. (Pl. 98, fig. 12).

Shell smooth, campanulate. Pores small, circular, irregularly scattered.
Horn stout, pyramidal, about as long as the shell. Peristome scarcely
constricted, with fifteen to twenty broad {1170}lamellar or lanceolate
feet, which are twice to three times as long as the shell, parallel and
vertical. (Very similar to _Petalospyris flabellum_, &c., Ehrenberg, 1875,
_loc. cit._, Taf. xxii. figs. 6-8, but without any trace of sagittal ring
or columella.)

_Dimensions._--Shell 0.05 to 0.08 diameter, feet 0.15 to 0.25 long.

_Habitat._--Central Pacific, Stations 266 to 268, depth 2700 to 2900
fathoms.



Subgenus 2. _Echinocalpis_, Haeckel, 1881, Prodromus, p. 427.

_Definition._--Shell spiny, covered with numerous spines or thorns (besides
the feet and the apical horn).


6. _Halicalyptra spinosa_, n. sp.

Shell spiny, ovate, inflate in the apical half. Pores irregular polygonal,
four to eight times as broad as the bars. Peristome constricted, half as
broad as the shell, with nine slender divergent feet, which like the apical
horn are curved, twice to three times as long as the shell and five to ten
times as long as the numerous bristles of the surface.

_Dimensions._--Shell 0.08 long, 0.06 broad; feet 0.15 to 0.25 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


7. _Halicalyptra castanella_, n. sp.

Shell spiny, nearly spherical. Pores irregular roundish. Peristome
constricted, scarcely one-third as broad as the shell, with twelve to
twenty slender, widely divergent feet, which like the horn are irregularly
curved, and longer than the shell. (Very similar to certain forms of the
Phæodarium _Castanella_, Pl. 113, fig. 2.)

_Dimensions._--Shell 0.13 diameter, feet 0.15 to 0.18 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 520. _Carpocanistrum_,[137] n. gen.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta)
without radial ribs in the wall of the campanulate or ovate shell. Mouth
with a corona of radial feet. Apex without horn.

The genus _Carpocanistrum_ differs from the similar preceding
_Halicalyptra_ in the loss of the apical horn. It is very nearly related to
the Dicyrtid _Carpocanium_ and may be easily confounded with it. But in the
latter the uppermost part of the shell-cavity includes a rudimentary
cephalis with a cortinar septum, whilst in _Carpocanistrum_ {1171}the
cephalis is entirely lost, and the inner cavity quite simple. The number of
the feet of the peristome is from nine to twenty, sometimes more. The mouth
is commonly more or less constricted.


1. _Carpocanistrum novenum_, n. sp.

Shell ovate, smooth, one and a third times as long as broad. Pores regular
circular, hexagonally framed, three times as broad as the bars, eight to
ten on the greatest breadth of the shell. Peristome strongly constricted,
one-third as broad as the shell, with nine large ovate lamellar, slightly
convergent feet.

_Dimensions._--Shell 0.08 long, 0.06 broad; mouth 0.02 broad.

_Habitat._--South Atlantic, Station 325, surface.


2. _Carpocanistrum flosculum_, n. sp. (Pl. 52, fig. 9).

Shell campanulate, rough, thick-walled, of equal breadth and length. Pores
regular circular, of the same breadth as the bars, twelve to fifteen on the
greatest breadth of the shell. Peristome slightly constricted, with twelve
elegant lanceolate, nearly vertical, a little convergent feet.

_Dimensions._--Shell 0.07 long, 0.07 broad; mouth 0.05 broad.

_Habitat._--Equatorial Atlantic, Station 347, surface.


3. _Carpocanistrum giganteum_, n. sp.

Shell ovate, smooth, very thick-walled, one and a third times as long as
broad. Pores very numerous and small, subregular circular, forty to fifty
on the greatest breadth of the shell, of about the same breadth as the
bars. Peristome small, constricted, scarcely one-fourth as broad as the
shell, with twelve to fifteen short triangular vertical feet.

_Dimensions._--Shell 0.28 to 0.31 long, 0.21 to 0.23 broad; mouth 0.06 to
0.07 broad.

_Habitat._--Fossil in Barbados.


4. _Carpocanistrum acephalum_, n. sp. (Pl. 52, fig. 10).

Shell ovate, smooth, thin-walled, one and a fifth times as long as broad.
Pores subregular circular, twice as broad as the bars, sixteen to twenty on
the greatest breadth of the shell. Peristome slightly constricted, with
fifteen to eighteen slender, slightly bent, nearly vertical, and parallel
feet, which are half as long as the shell.

_Dimensions._--Shell 0.12 long, 0.1 broad; mouth 0.07 broad.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


{1172}5. _Carpocanistrum evacuatum_, n. sp. (Pl. 52, fig. 11).

Shell urceolate, smooth, thin-walled, one and a half times as long as
broad. Pores regular circular, sixteen to twenty on the greatest breadth of
the shell. Peristome slightly constricted, with twenty to twenty-five small
triangular vertical feet.

_Dimensions._--Shell 0.1 long, 0.07 broad; mouth 0.05 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


6. _Carpocanistrum pyriforme_, Haeckel.

  _Lithocarpium pyriforme_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 97,
  Taf. iii. fig. 10.

Shell pear-shaped or subspherical, one and a fourth times as long as broad.
Pores roundish, polygonally framed (or with square meshes ?). Peristome
strongly constricted, one-fourth as broad as the shell, somewhat tubular,
with twelve to twenty short vertical and parallel feet. The position of
this species is doubtful; perhaps it represents a peculiar genus.

_Dimensions._--Shell 0.17 long, 0.14 broad; mouth 0.035 broad.

_Habitat._--Fossil in Tertiary rocks of Sicily (Grotte) Stöhr.



Genus 521. _Arachnocalpis_,[138] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with
an ellipsoidal or nearly spherical double shell; outer shell arachnoidal or
spongy. Peristome small, constricted with a corona of numerous radial feet.
No apical horn.

The genus _Arachnocalpis_ differs from the other Archiphormida by
possessing a double shell (like _Peripyramis_). The large shell, reaching
nearly half a millimeter in length is either ellipsoidal or nearly
spherical, and composed of an inner primary and an outer secondary shell.
Its network is very delicate, in the outer envelope either spongy or
arachnoidal. This very remarkable genus has probably no true relation to
the other Archiphormida but has been derived from true #Calpoidea#
(_Mitrocalpis_) by development of a corona around the mouth.


1. _Arachnocalpis ellipsoides_, n. sp. (Pl. 98, fig. 13).

Shell ellipsoidal, one and a half times as long as broad, on the apical
pole hemispherical, on the basal pole coronate, with an elegant prominent
funnel-shaped peristome, which is one-eighth as broad as the shell,
fenestrated by very fine pores, and bears fifteen to twenty short conical
divergent teeth. Inner shell with irregular polygonal meshes of very
different size, separated by thin, {1173}finely-denticulate bars. Outer
spongy shell very delicate, arachnoidal, with numerous prominent conical
spongy papillæ. Central capsule ellipsoidal, half as long and broad as the
shell.

_Dimensions._--Shell 0.46 long, 0.32 broad; mouth 0.045 broad.

_Habitat._--Central Pacific, Stations 271 to 274, surface.


2. _Arachnocalpis sphæroides_, n. sp.

Shell spheroidal, of the same structure as the preceding ellipsoidal
species, with the same form of the spongy envelope; differing from it in
the globose form and the shorter peristome, bearing only nine or ten small
conical divergent teeth. Central capsule spherical.

_Dimensions._--Shell 0.3 diameter, mouth 0.04 broad.

_Habitat._--Central Pacific, Stations 265 to 270, surface.



Subfamily 2. ARCHIPHÆNIDA, Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Phænocalpida# with the basal mouth of the shell fenestrated
(vel Monocyrtida multiradiata clausa).



Genus 522. _Phænocalpis_,[139] n. gen.

_Definition._--#Archiperida# (vel Monocyrtida multiradiata clausa) with an
internal axial simple columella, prolonged outside into an apical horn.

The genus _Phænocalpis_ and the following _Phænoscenium_ comprise those
Archiphænida in which the vertical axis of the shell-cavity is occupied by
a simple or branched columella, arising from the centre of the base and
prolonged into an apical horn. This columella may be either the vertical
rod of a _Plectaniscus_ or the remnant of an original ring of
_Petalospyris_. The latter genus differs by its sagittal constriction.


1. _Phænocalpis petalospyris_, n. sp. (Pl. 97, fig. 4).

Shell subspherical, rough, with irregular, roundish pores, larger than the
bars. Columella straight, central, thin, prolonged into a large apical horn
with three dentate edges. Six basal feet curved, divergent, lamellar, with
a middle rib and dentate edges.

_Dimensions._--Shell 0.07 long, 0.05 broad; horn and feet 0.06 long.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


{1174}2. _Phænocalpis ocellata_, Haeckel.

  _Petalospyris ocellata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. xxii. fig. 9.

Shell subspherical, smooth, with irregular roundish pores, about as broad
as the bars. Columella slightly curved and excentric, prolonged into a
slender conical horn of the same length. Six basal feet similar to the
horn, slightly divergent.

_Dimensions._--Shell 0.06 long, 0.07 broad; horn and feet 0.05 long.

_Habitat._--Fossil in Barbados.


3. _Phænocalpis carinata_, Haeckel.

  _Petalospyris carinata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. xxii. fig. 6.

Shell campanulate, rough, with irregular roundish pores, smaller than the
bars. Columella straight, central, prolonged into a stout conical horn of
the same length. Nine basal feet slender, triangular, longer than the
shell, nearly vertical, with a middle rib in the basal half.

_Dimensions._--Shell 0.05 long, 0.06 broad; horn 0.04 long, feet 0.08 long.

_Habitat._--Fossil in Barbados.


4. _Phænocalpis flabellum_, Haeckel.

  _Petalospyris flabellum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, Taf. xxii. fig. 7.

Shell campanulate smooth, with very small circular pores, half as broad as
the bars. Columella straight, central, prolonged into a pyramidal horn of
half the length. Twelve to fifteen basal feet lamellar, linear, twice to
three times as long as the shell, parallel and vertical, pointed at the
distal end.

_Dimensions._--Shell 0.04 long, 0.05 broad; horn 0.02 long, feet 0.1 to
0.12 long.

_Habitat._--Fossil in Barbados.



Genus 523. _Phænoscenium_,[140] n. gen.

_Definition._--#Archiphænida# (vel Monocyrtida multiradiata clausa) with an
internal axial branched columella, prolonged outside into an apical horn.

The genus _Phænoscenium_ differs from the preceding _Phænocalpis_ in the
branched columella, which is connected by three or six ascending branches
with the inner wall of the shell. It bears therefore to the latter the same
relation that _Cladoscenium_ exhibits to _Euscenium_. The former genera may
have been derived from the latter by interpolation of new interradial feet
between the three primary perradial feet.


{1175}1. _Phænoscenium hexapodium_, n. sp. (Pl. 98, fig. 9).

Shell campanulate, smooth, about as long as broad. Network delicate, with
irregular polygonal pores and thin bars. Columella with four to six
ascending three-branched verticils, prolonged into the conical hollow
apical horn (with six to eight smaller verticils) which is about as long as
the shell. Six basal feet curved, divergent, of the same length, with
pinnate middle rod.

_Dimensions._--Shell 0.1 long, 0.11 broad; horn and feet 0.08 to 0.09 long.

_Habitat._--Central Pacific, Section 271, depth 2425 fathoms.


2. _Phænoscenium cladopodium_, n. sp.

Shell campanulate, conical, smooth, somewhat broader than long. Network
with irregular roundish pores, about as broad as the bars. Columella with a
single verticil of three ascending branches. Horn pyramidal, stout, as long
as the shell, with three dentate edges. Six feet divergent, slightly
curved, very unequal; three primary (or perradial) very large, longer than
the shell, three sided pyramidal, with three dentate edges; three secondary
(or interradial) much smaller, simple, shorter than the shell.

_Dimensions._--Shell 0.05 long, 0.06 broad; horn and feet 0.04 to 0.07
long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


3. _Phænoscenium polypodium_, n. sp.

Shell subspherical, about as long as broad, smooth. Network with regular
circular pores, twice as broad as the bars. Columella with two verticils of
three ascending branches, prolonged into a stout conical horn of twice the
length. Twelve to fifteen conical curved divergent feet, about as long as
the shell. The three primary feet are directly connected with the base of
the columella.

_Dimensions._--Shell 0.08 diameter, horn 0.15 long, feet 0.07 to 0.09 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



Genus 524. _Calpophæna_,[141] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiphænida# (vel Monocyrtida multiradiata clausa) with an
apical horn and simple internal cavity of the shell without axial
columella.

The genus _Calpophæna_ and the following closely tied _Archiphæna_ differ
from the two preceding genera of Archiphænida in the simple shell cavity,
which encloses no columella. They may be derived either from the preceding
_Phænocalpis_ by loss of the columella, or directly from the Zygospyrida by
reduction of the sagittal constriction and loss of the primary ring.
Different subgenera may be distinguished in _Calpophæna_ according either
to the number of the feet or to their shape (being simple or branched).



{1176}Subgenus 1. _Acrocorona_, Haeckel, 1881, Prodromus, p. 430.

_Definition._--Feet simple, not branched nor forked.


1. _Calpophæna tetrarrhabda_, n. sp.

Shell subspherical, tuberculate, with subregular circular pores. Apical
horn conical, about as long as the shell. Basal plate with a regular cross
of four equal cortinar pores, separated by four bars; these are crossed in
the sagittal and frontal diameter, and prolonged into four equal conical
divergent feet, about as long as the shell.

_Dimensions._--Shell 0.1 diameter, horn and feet 0.1 to 0.12 long.

_Habitat._--South Pacific, Station 297, depth 1775 fathoms.


2. _Calpophæna hexarrhabda_, n. sp. (Pl. 53, figs. 17, 18).

Shell subspherical, rough, with irregular roundish pores. Apical horn
conical, shorter than the shell. Basal plate (fig. 18) with three pairs of
triangular pores, two larger (cardinal) pores in the middle, two smaller
(cervical) at the dorsal, and two intermediate (jugular) at the ventral
side. The bars between them are prolonged into six equal cylindrical
divergent feet, nearly as long as the shell, provided with a spiny knob at
the end.

_Dimensions._--Shell 0.09 long, 0.08 broad; horn and feet 0.06 to 0.08
long.

_Habitat._--Tropical Pacific, Station 224, depth 1850 fathoms.


3. _Calpophæna ennearrhabda_, n. sp.

Shell subspherical, spiny, with irregular, roundish pores. Apical horn
cylindrical, longer than the shell. Basal plate with nine collar pores,
three larger central alternating with three pairs of smaller peripheral
(like Pl. 87, fig. 2). Corona with nine slender cylindrical, slightly
curved, divergent feet, somewhat longer than the shell.

_Dimensions._--Shell 0.11 long, 0.1 broad; horn and feet 0.12 to 0.15 long.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


4. _Calpophæna enneaphylla_, n. sp.

Shell ovate, smooth, with regular circular pores. Apical horn pyramidal,
half as long as the shell. (Basal plate with four cortinar pores?) Corona
with nine broad, lamellar, truncate, vertical feet, about as long as the
horn.

_Dimensions._--Shell 0.12 long, 0.09 broad; horn and feet 0.06 long.

_Habitat._--Central Pacific, Station 271, surface.


{1177}5. _Calpophæna petalospyris_, n. sp.

Shell campanulate, tuberculate, with irregular, roundish pores. Apical horn
conical, shorter than the shell. (Basal plate with nine pores?) Corona with
twelve to twenty broad, lamellar, truncate, vertical feet, of different
sizes, somewhat irregular.

_Dimensions._--Shell 0.08 long, 0.09 broad; horn and feet 0.07 to 0.12
long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.



Subgenus 2. _Cladocorona_, Haeckel, 1881, Prodromus, p. 430.

_Definition._--Feet branched or forked.


6. _Calpophæna tetracorethra_, n. sp.

Shell subspherical, smooth, with irregular, roundish pores. Basal plate
with four larger pores. Apical horn and the four divergent basal feet of
equal size and similar form, three to four times as long as the shell,
slender, bristle-shaped, curved, in the distal half irregularly branched.
(Very similar to the remarkable _Tetraspyris tetracorethra_, Pl. 53, figs.
19, 20, but with shorter appendages and with simple spherical shell, which
exhibits no trace of sagittal ring and constriction.)

_Dimensions._--Shell 0.12 diameter, horn and feet 0.3 to 0.5 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


7. _Calpophæna hexacorethra_, n. sp.

Shell subspherical, smooth, similar to the preceding species. Basal plate
with six pores. Apical horn and the six divergent feet twice to three times
as long as the shell, bristle-shaped, irregularly curved and branched.
(Similar to _Hexaspyris hexacorethra_, Pl. 95, fig. 8, but without sagittal
ring and constriction.)

_Dimensions._--Shell 0.11 long, 0.13 broad; horn and feet 0.2 to 0.3 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



Genus 525. _Archiphæna_,[142] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiphænida# (vel Monocyrtida multiradiata clausa), with
simple internal cavity of the shell, without apical horn and axial
columella.

The genus _Archiphæna_ has the same simple cavity of the shell as the
preceding _Calpophæna_, but differs from it in the loss of the apical horn.
It bears therefore to the latter the same relation that _Gorgospyris_ does
to _Petalospyris_. The two former genera may be derived from the two latter
by loss of the sagittal ring and constriction.



{1178}Subgenus 1. _Coronophæna_, Haeckel, 1881, Prodromus, p. 429.

_Definition._--Feet simple, not branched nor forked.


1. _Archiphæna gorgospyris_, n. sp. (Pl. 98, figs. 10, 10_a_).

Shell hemispherical, smooth, with small subregular, circular pores. Collar
septum with four large pores (fig. 10_a_). Twelve to fifteen feet,
divergent, lamellar, truncate, about as long as the shell. (Similar to
certain forms of _Gorgospyris_, Pl. 87, figs. 1 to 3, but with simple shell
cavity, without sagittal ring and constriction, and without a columella.)

_Dimensions._--Shell 0.08 long, 0.04 broad; feet 0.03 to 0.04 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


2. _Archiphæna corona_, n. sp.

Shell crown-shaped, somewhat broader than long, at the base flattened,
papillate, with irregular roundish pores. Twenty to twenty-five feet,
broad, lamellar, truncate, nearly vertical, about twice as long as the
shell.

_Dimensions._--Shell 0.1 long, 0.12 broad; feet 0.2 to 0.22 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Subgenus 2. _Stephanophæna_, Haeckel, 1881, Prodromus, p. 429.

_Definition._--Feet branched or forked.


3. _Archiphæna stephanoma_, n. sp.

Shell campanulate, somewhat longer than broad, with subregular, circular
pores. Margin of the flattened base with a corona of about twenty unequal
feet, which are partly simple, partly irregularly branched, and about as
long as the shell.

_Dimensions._--Shell 0.11 long, 0.03 broad; feet 0.08 to 0.12 long.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Family LXI. #CYRTOCALPIDA#, n. fam.

  Archicorida et Archicapsida, Haeckel, 1881, Prodromus, pp. 427, 428.

_Definition._--#Monocyrtida# eradiata. (#Cyrtoidea# with a simple, not
jointed shell, representing a simple cephalis without radial apophyses.)

The family #Cyrtocalpida#, composed of the Archicorida and Archicapsida of
my {1179}Prodromus, comprises those #Cyrtoidea# in which the lattice-shell
is quite simple, without transverse constriction, and without radial
apophyses. The two subfamilies differ in the shape of the basal mouth,
which in the Archicorida is a simple wide opening, but in the Archicapsida
is closed by a lattice-plate.

Only a few species of this family were formerly known. Ehrenberg, in 1838,
founded upon these the genus _Cornutella_, one of the three oldest genera
of Polycystina (_Cornutella_, _Lithocampe_, _Haliomma_). In 1862 I
described some living forms, with a central capsule, as _Cyrtocalpis_. The
Challenger collection contains a large number of new genera and species.

Probably the family Cyrtocalpida is an artificial group, comprising two or
more different subfamilies of very different origin. The Cornutellida
(_Cornutella_, _Cornutanna_) have probably been derived from the
Sethocorida by loss of the cephalis, so that their conical shell represents
a thorax alone. The Mitrocalpida on the other hand (genera 528-531) may be
originally simple ovate shells (like _Gromia_ and _Lecythium_), arising
independently from the Nassellida. The Archicapsida (_Halicapsa_,
_Archicapsa_) are probably derived from the Zygospyrida (_Dictyospyris_,
_Circospyris_) by loss of the sagittal ring and constriction. This is
nearly certain, when the three or four typical cortinar pores appear in
their basal plate. Some forms of _Halicapsa_ may be easily confounded with
some forms of Prunoidea (_Lithapium_).

Those Cyrtocalpida, which possess a central capsule with three or four
lobes, are probably derived from Tripocyrtida by loss of the three feet, or
from Sethocyrtida by loss of the cephalis, since the lobes indicate the
original presence of cortinar pores and of a cephalis. Those Cyrtocalpida,
however, in which a simple ovate shell encloses a simple central capsule
without lobes, may be original "Monocyrtida eradiata," without relation to
any radial ancestral forms.

_Synopsis of the Genera of Cyrtocalpida._

  -------------------------------------------------------------------------
  I. Subfamily Archicorida. Basal mouth of the shell a simple wide opening.
                            --------------------
     Shell with simple lattice-work (not double or spongy).
  -------------------------------------------------------------------------
  Shell conical, gradually   { With horn,    526. _Cornutella_.
   dilated towards           {
   the mouth.                { No horn,      527. _Cornutanna_.

  Shell ovate or urceolate,  { With horn,    528. _Archicorys_.
   with constricted          {
   mouth.                    { No horn,      529. _Cyrtocalpis_
  -------------------------------------------------------------------------
  Shell not simply latticed.
  -------------------------------------------------------------------------
  Shell ovate, double, with an external      530. _Mitrocalpis_.
   mantle,

  Shell ovate, with spongy irregular,
   lattice-work                              531. _Spongocyrtis_.
  -------------------------------------------------------------------------
  II. Subfamily Archicapsida. Mouth closed by a lattice plate.
  -------------------------------------------------------------------------
  Shell with an apical horn,                 532. _Halicapsa_.

  Shell without horn on the apex,            533. _Archicapsa_.



{1180}Subfamily 1. ARCHICORIDA, Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Cyrtocalpida#, with the basal mouth of the shell open (vel
Monocyrtida eradiata aperta).



Genus 526. _Cornutella_,[143] Ehrenberg, 1838, Abhandl. d. k. Akad. d.
Wiss. Berlin, p. 128.

_Definition._--#Archicorida# with conical shell, gradually dilated towards
the wide open mouth. Apex armed with a horn.

The genus _Cornutella_ is one of the three oldest genera of Polycystina,
described by Ehrenberg, in 1838 (_Cornutella_, _Lithocampe_, and
_Haliomma_). He afterwards enumerated, in 1872 and 1875, a large number of
fossil and living species, the majority of which, however, belong to other
genera of Monocyrtida and Dicyrtida (at least six or seven different
genera). We retain here as the true type of the genus the oldest known
species:--_Cornutella clathrata_, and the nearly allied forms _Cornutella
stylophæna_, _Cornutella mitra_, _Cornutella circularis_, &c. The simple
conical shell exhibits no distinct trace of an original cephalis, excepting
the apical horn; it may have originated either independently, or been
derived from _Sethoconus_, by loss of the cephalis.



Subgenus 1. _Cornutellium_, Haeckel.

_Definition._--Axis of the conical shell straight. Pores polygonal, or
roundish with polygonal frames.


1. _Cornutella hexagona_, n. sp. (Pl. 54, fig. 9).

Shell slender, conical, with straight outlines. Pores subregular,
hexagonal, gradually increasing in size towards the mouth; in about ten to
twelve longitudinal series, in the upper part very small. Horn slenderly
conical, nearly bristle-shaped, long.

_Dimensions._--Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

_Habitat._--Central Pacific, Stations 265 to 274, surface, and at different
depths.


2. _Cornutella sethoconus_, n. sp. (Pl. 54, fig. 10).

Shell slender, conical, with undulate outlines. Pores subregular,
hexagonal, gradually increasing in size towards the mouth, in about fifteen
to eighteen longitudinal series, in the upper part circular. Horn small,
conical, short. The network is not so delicate as in the preceding similar
species.

_Dimensions._--Shell 0.12 to 0.16 long, 0.06 to 0.08 broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


{1181}3. _Cornutella distenta_, Ehrenberg.

  _Cornutella distenta_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. vi. III. fig. 3.

Shell slender, conical, with straight outlines. Pores small, circular,
regularly disposed in six to eight alternating longitudinal rows, each pore
surrounded by a large rhombic frame. The connected frames form together a
regular rhombic framework with obliquely crossed crests. Horn conical,
stout, large.

_Dimensions._--Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

_Habitat._--North Pacific, Californian Sea, depth 2600 fathoms, Ehrenberg.


4. _Cornutella stiligera_, Ehrenberg.

  _Cornutella stiligera_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 1;
  Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 68, Taf. ii. fig. 3.

Shell slender, conical, with straight outlines. Pores subregular, rhombic
or nearly square, disposed in oblique series, separated by parallel
obliquely ascending rings, which are crossed by interrupted parallel bars.
Horn slenderly conical or bristle-shaped, thin and long.

_Dimensions._--Shell 0.08 to 0.12 long, 0.03 to 0.04 broad.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Cornutissa_, Haeckel, 1881, Prodromus, p. 427.

_Definition._--Axis of the conical shell straight. Pores circular or
roundish, without polygonal frames.


5. _Cornutella circularis_, Ehrenberg.

  _Cornutella circularis_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. ii. fig. 4.

Shell wide, conical or funnel-shaped, with straight outlines. Pores very
large, circular, ten to twenty times as broad as the bars, in about nine to
twelve longitudinal alternating rows, increasing gradually towards the
mouth. Horn very large, cylindrical.

_Dimensions._--Shell 0.1 to 0.15 long, 0.08 to 0.12 broad.

_Habitat._--Fossil in Barbados.


6. _Cornutella mitra_, Ehrenberg.

  _Cornutella mitra_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. ii. fig. 8.

Shell wide, conical, campanulate, with convex outlines. Pores subregular,
circular, nearly equal in size, not regularly disposed in rows. Horn
conical, stout.

_Dimensions._--Shell 0.12 to 0.16 long, 0.08 to 0.12 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms; also fossil
in Barbados.


{1182}7. _Cornutella clathrata_, Ehrenberg.

  _Cornutella clathrata_, Ehrenberg, 1838, Monatsber. d. k. preuss. Akad.
  d. Wiss. Berlin, p. 129; Mikrogeol., Taf. xxii. fig. 39.

  _Cornutella clathrata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, Taf. ii. fig. 9.

Shell wide, conical with slightly convex outlines. Pores regular, circular,
gradually increasing in size towards the mouth, disposed in twelve to
fifteen longitudinal alternating rows. Horn short and stout, conical.
(Compare _Cornutella curvata_.)

_Dimensions._--Shell 0.15 to 0.2 long, 0.06 to 0.09 broad.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific; also fossil in
tertiary rocks of Barbados, Nikobar and Sicily.


8. _Cornutella stylophæna_, Ehrenberg.

  _Cornutella stylophæna_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. vi. III. fig. 1.

  ? _Cornutella tumens_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. vi. III. fig. 4.

Shell slender, conical, with undulate outlines. Pores subregular, circular,
gradually increasing in size, disposed in six to nine quincuncial
alternating longitudinal rows.  Horn very long, cylindro-conical, sometimes
about as long as the shell.

_Dimensions._--Shell 0.1 to 0.13 long, 0.04 to 0.06 broad.

_Habitat._--North Pacific, Californian Sea, depth 2600 fathoms.


9. _Cornutella granulata_, Ehrenberg.

  _Cornutella granulata_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. vi. III. fig. 5.

Shell slender, conical, nearly cylindrical, with straight outlines, rounded
at the apex. Pores very small and numerous, punctiform, disposed into very
numerous parallel transverse rows. Horn small, conical (may be perhaps the
shell of a Tintinnoid Infusorium?).

_Dimensions._--Shell 0.08 long, 0.02 broad.

_Habitat._--North Pacific, Californian Sea, depth 2600 fathoms.


10. _Cornutella annulata_, Ehrenberg.

  _Cornutella annulata_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. ii. fig. 16.

Shell slender, conical, nearly cylindrical, with straight outlines, rounded
at the apex. Pores small and numerous, regular circular, of equal size,
regularly disposed in ten to fifteen parallel transverse series. Horn
bristle-shaped. (Compare _Artostrobus annulatus_, _Cornutella annulata_,
Bailey.)

_Dimensions._--Shell 0.1 to 0.13 long, 0.03 to 0.04 broad.

_Habitat._--Cosmopolitan, Atlantic, Pacific, surface.



{1183}Subgenus 3. _Cornutosa_, Haeckel, 1881, Prodromus, p. 427.

_Definition._--Axis of the conical shell curved. Pores circular or
roundish.


11. _Cornutella curvata_, Haeckel.

  _Cornutella clathrata_, var., Ehrenberg, 1854, Mikrogeol., Taf. xxii.
  figs. 39_a_, _b_, _c_.

  _Cornutosa clathrata_, Haeckel, 1881, Prodromus, p. 427.

Shell slender, conical, with curved axis; the curve lies in one plane and
is not spirally convoluted. Pores subregular, circular, of nearly equal
size, quincuncially disposed. Horn short, conical.

_Dimensions._--Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

_Habitat._--Fossil in tertiary rocks of Sicily (Caltanisetta).


12. _Cornutella spiralis_, n. sp.

  _Cornutura spiralis_, Haeckel, 1881, Prodromus, p. 427.

Shell slender, conical, nearly cylindrical, very long, spirally contorted;
its axis is an ascending spiral line with two or three windings, widely
distant. Pores irregular, square, small and numerous.

_Dimensions._--Shell 0.2 to 0.25 long, 0.05 to 0.08 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 527. _Cornutanna_,[144] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archicorida# with conical shell, gradually dilated towards
the wide open mouth. Apex without horn.

The genus _Cornutanna_ has the same simple conical shell as the preceding
_Cornutella_, but differs from it in the total absence of an apical horn.
It bears therefore to the latter the same relation that _Cyrtocalpis_ does
to _Archicorys_. It may be derived from _Sethoconus_ by complete reduction
of the cephalis and its horn.


1. _Cornutanna orthoconus_, n. sp.

Shell slender, conical, with straight axis and straight outlines. Pores
subregular, circular, quincuncially disposed in nine to twelve alternating
longitudinal series, gradually increasing in size towards the mouth.

_Dimensions._--Shell 0.1 to 0.12 long, 0.03 to 0.04 broad.

_Habitat._--Central Pacific, Stations 270 to 274, surface.


{1184}2. _Cornutanna cyrtoconus_, n. sp.

Shell slender, conical, with curved axis; the curve lies in one plane as in
the similar _Cornutella curvata_; the pores are smaller and more numerous
than in this latter species, and the rounded apex bears no horn.

_Dimensions._--Shell 0.12 to 0.16 long, 0.05 to 0.07 broad.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


3. _Cornutanna loxoconus_, n. sp.

Shell wide, conical, with irregularly curved axis; the parts of the curve
do not lie in one plane. Pores very small and numerous, of nearly equal
size.

_Dimensions._--Shell 0.2 long, 0.12 broad.

_Habitat._--Tropical Pacific, Station 225, depth 4475 fathoms.



Genus 528. _Archicorys_,[145] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archicorida# with simple urceolate or ovate shell,
constricted towards the mouth. Apex armed with a horn.

The genus _Archicorys_ and the following closely allied _Cyrtocalpis_
differ from the two preceding genera in the ovate or urceolate form of the
shell, which is more or less constricted towards the terminal mouth. The
upper pole in _Archicorys_ bears an apical horn, which is absent in
_Cyrtocalpis_. The origin of these two genera may be the same, probably
arising directly from Nassellida, and independently of the triradiate
#Cyrtoidea# or bilocular #Spyroidea#. (Compare p. 1179.)


1. _Archicorys galea_, n. sp.

Shell smooth urceolate. Pores large, in the middle part hexagonal, towards
both ends smaller and polygonal. Apical horn stout, three-sided pyramidal,
half as long as the shell. Mouth with a short tubular peristome, about
one-third as broad as the shell.

_Dimensions._--Shell (without horn) 0.15 long, 0.12 broad; horn 0.07 long,
mouth 0.05 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


2. _Archicorys ampulla_, n. sp.

Shell smooth, thin-walled, bottle-shaped, in the upper half conical, in the
lower half inflate, subspherical. Pores subregular, circular, of the same
breadth as the bars. Horn conical, stout, {1185}/about one-third as long as
the shell. Mouth truncate, without peristome, about half as broad as the
shell.

_Dimensions._--Shell 0.15 long, 0.1 broad; horn 0.05, mouth 0.05.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Archicorys microstoma_, n. sp. (Pl. 51, fig. 12).

Shell rough, thick-walled, ovate. Pores large, subregular, circular, twice
to four times as broad as the bars. Horn small, conical, not larger than
one pore. Mouth very small, truncate, scarcely larger than one pore.

_Dimensions._--Shell 0.1 long, 0.07 broad; horn 0.012, mouth 0.015.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


4. _Archicorys globosa_, n. sp.

Shell nearly spherical, thorny, thick-walled. Pores very large, circular,
separated by spinulate frames, smaller towards each pole. Horn conical,
large, nearly as long as the radius of the shell; mouth truncate, simple,
about one-third as broad as the shell.

_Dimensions._--Shell diameter 0.13, horn 0.06, mouth 0.04.

_Habitat._--Fossil in Barbados.


5. _Archicorys ovata_, n. sp. (Pl. 51, fig. 10).

Shell ovate, rough, thick-walled. Pores regular, circular, of equal size,
very small and numerous, quincuncially disposed. Horn small, conical,
sometimes (as in the figured specimen) rudimentary. When it becomes lost,
the species may be called _Cyrtocalpis ovata_. Mouth truncate, small,
simple, one-sixth as broad as the shell.

_Dimensions._--Shell 0.2 long, 0.15 broad; horn 0.01 to 0.03 long, mouth
0.03 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.



Genus 529. _Cyrtocalpis_,[146] Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 835.

_Definition._--#Archicorida# with simple urceolate or ovate shell,
constricted towards the mouth. Apex without horn.

The genus _Cyrtocalpis_ comprises a large number of common, very primitive
Monocyrtida, which in the simple ovate or urceolate form of the shell
resemble the well known _Gromia_ among the Thalamophora. Its basal mouth is
more or less constricted, as in {1186}the preceding genus _Archicorys_,
from which it differs in the total absence of an apical horn. There is no
trace of any triradial structure, excepting in some smaller species, in
which the basal part of the central capsule is trilobate; these may be
derived from the Dicyrtides _Sethocorys_ or _Dictyocephalus_, by loss of
the cephalis and the cortinar septum. But the larger species, which have a
quite simple, ovate, central capsule (Pl. 51, fig. 13), have probably an
independent origin, from _Cystidium_.


1. _Cyrtocalpis urceolus_, n. sp. (Pl. 51, fig. 13).

Shell smooth, urceolate, with very delicate and elegant network. Pores in
the middle part large, regular, hexagonal, towards each pole smaller,
irregular, roundish or polygonal. Mouth with broad, hyaline, annular
peristome, about one-third as broad as the shell.

_Dimensions._--Shell 0.16 long, 0.12 broad; mouth 0.05 broad.

_Habitat._--Mediterranean (Portofino near Genoa), surface.


2. _Cyrtocalpis reticulum_, n. sp.

Shell smooth, urceolate, very similar to the preceding species, but
differing from it in the densely reticulated framework of the shell, which
is composed of very numerous and small, irregular, polygonal meshes of
nearly equal size. Mouth without peristome, half as broad as the shell.

_Dimensions._--Shell 0.18 long, 0.15 broad; mouth 0.07 broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


3. _Cyrtocalpis amphora_, Haeckel.

  _Cyrtocalpis amphora_, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v.
  fig. 2.

Shell smooth, urceolate with regular, circular pores of equal size, of
about the same breadth as the bars. Mouth with smooth peristome, about half
as broad as the shell.

_Dimensions._--Shell 0.12 long, 0.08 broad; mouth 0.04 broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific; surface, and at
various depths.


4. _Cyrtocalpis urna_, Stöhr.

  _Cyrtocalpis urna_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf. iii.
  fig. 7.

Shell smooth, urceolate, with subregular, circular pores of different
sizes, gradually increasing towards the mouth, of about the same breadth as
the bars. Mouth without peristome (?), about half as broad as the shell.

_Dimensions._--Shell 0.09 long, 0.06 broad; mouth 0.035 broad.

_Habitat._--Fossil in tertiary rocks of Sicily (Grotte).


{1187}5. _Cyrtocalpis sethopora_, n. sp. (Pl. 52, fig. 4).

Shell smooth, urceolate, very thin-walled, with large irregular roundish
meshes, each of which is closed by a thin porous sieve-plate. Mouth
two-thirds as broad as the shell, with a broad, emarginate, longitudinally
striped peristome. (Perhaps the shell of a Tintinnoid Infusorium?)

_Dimensions._--Shell 0.08 long, 0.05 broad; mouth 0.03 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


6. _Cyrtocalpis compacta_, n. sp. (Pl. 52, figs. 7, 8).

Shell smooth, ovate, very thick-walled, with small, subregular, circular
pores of equal size, perpendicularly perforating the wall, about half as
broad as the bars. Mouth small, only one-third as broad as the compact
shell. (Perhaps a reduced _Lithocampe_ or _Lithomitra_?)

_Dimensions._--Shell 0.08 long, 0.04 broad; mouth 0.015 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms; also fossil
in Barbados.


7. _Cyrtocalpis lithomitra_, n. sp. (Pl. 52, figs. 5, 6).

Shell smooth, slender, ovate, nearly cylindrical, with small subregular,
circular pores, which are disposed in nine to twelve transverse rows, and
obliquely ascending perforate the wall. Mouth wide, without peristome,
about two-thirds as broad as the shell. (Compare _Lithomitra_, Pl. 79.)

_Dimensions._--Shell 0.09 long, 0.045 broad; mouth 0.03 broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; also fossil
in Barbados.


8. _Cyrtocalpis ovulum_, n. sp.

  _Cyrtocalpis obliqua_, var. _ovulum_, Haeckel, 1862, Monogr. d. Radiol.,
  p. 286, Taf. v. fig. 3.

Shell smooth, broad, ovate, with very numerous and small regular circular
pores, quincuncially disposed, twice as broad as the bars. Mouth without
peristome, about half as broad as the shell.

_Dimensions._--Shell 0.09 long, 0.047 broad; mouth 0.04 broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.


9. _Cyrtocalpis obliqua_, Haeckel.

  _Cyrtocalpis obliqua_, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v.
  figs. 4-11.

Shell smooth, irregularly ovate, more or less oblique, variable in size and
form, sometimes nearly spherical, at other times subcylindrical. Pores
subregular, circular, once or twice the breadth of the bars.  Mouth simple
without peristome, about half as broad as the shell.

_Dimensions._--Shell 0.07 to 0.1 long, 0.05 to 0.08 broad; mouth 0.03 to
0.04 broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.


{1188}10. _Cyrtocalpis gromia_, n. sp. (Pl. 51, fig. 11).

Shell rough, ovate, very thick-walled, with subregular, circular pores of
somewhat variable size. The diameter of the internal, simple, subspherical
cavity is five to six times as great as the thickness of the wall. Mouth
tubular, cylindrical, very narrow, only one-sixth as broad as the shell.

_Dimensions._--Shell 0.16 long, 0.11 broad; mouth 0.02 broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



Genus 530. _Mitrocalpis_,[147] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archicorida# with a double ovate or ellipsoidal shell,
composed of two parallel lattice-plates, which are connected by numerous
beams. Apex without horn.

The genus _Mitrocalpis_ and the following closely allied _Spongocyrtis_
differ from the four preceding genera of Archicorida in the complicated
structure of the shell-wall, which in the former is double, in the latter
spongy. The mouth is in both genera constricted, narrow, and the apex
without a horn. _Mitrocalpis_ has been derived probably from _Cyrtocalpis_
in the same way as _Peripyramis_ from _Bathropyramis_, by development of
spines on the surface of the shell, which at equal distances from the
latter become connected by branches, thus forming an outer envelope.


1. _Mitrocalpis palliata_, n. sp.

Shell ellipsoidal, large, one and a third times as long as broad. Inner
shell very thin-walled, with irregular, polygonal pores of very variable
size and form. From its nodal points there arise numerous bristle-shaped
radial beams, about as long as the diameter of the mouth, which are
connected at equal distances from the surface by delicate threads, forming
the outer enveloping shell. The surface of the latter is smooth. The thin
bars of the inner shell are twice to four times as broad as those of the
outer. Mouth about one-seventh as broad as the shell, with a short tubular
peristome.

_Dimensions._--Shell 0.35 long, 0.27 broad; mouth 0.04, distance of both
shells 0.037.

_Habitat._--Central Pacific, Station 271, surface.



Genus 531. _Spongocyrtis_,[148] Dunikowski.

  _Spongocyrtis_, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien,
  vol. xlv. p. 31.

_Definition._--#Archicorida# with a spongy ovate shell, the wall of which
is composed of irregular spongy wickerwork. Apex without horn.

The genus _Spongocyrtis_ differs from most other Monocyrtida in the spongy
structure of the shell, which is found in only very few other genera of
#Cyrtoidea#, e.g., in _Spongopyramis_ and _Spongomelissa_. It has been
derived either from the similar {1189}_Cyrtocalpis_ by development of
irregular spongy wickerwork on the surface of the simple lattice-shell; or
from _Arachnocalpis_ (Pl. 98, fig. 13) by loss of the peristome.


1. _Spongocyrtis montis ovis_, Dunikowski.

  _Spongocyrtis montis ovis_, Dunikowski, 1882, Denkschr. d. k. Akad. d.
  Wiss. Wien, vol. xlv. p. 31, Taf. vi. figs. 67, 68.

Shell broad, ovate, rough, spongy, thick-walled; length to the breadth =
4 : 3. Spongy framework very dense and dark, with very small roundish
pores. Mouth constricted, with a short tubular peristome, about one-third
as broad as the shell.

_Dimensions._--Shell 0.35 long, 0.26 broad; mouth 0.08 broad.

_Habitat._--Fossil in the Alpine Lias (Schafberg bei Salzburg, Dunikowski).


2. _Spongocyrtis arachnoides_, n. sp.

Shell ellipsoidal, spiny, spongy, thin-walled; length to the breadth =
3 : 2. Spongy framework loose and delicate, with irregular polygonal meshes
and arachnoidal thread-like bars. Mouth constricted, without peristome,
about one-fifth as broad as the shell. (Very similar to _Arachnocalpis
ellipsoides_, Pl. 98, fig. 13, but without corona around the mouth.)

_Dimensions._--Shell 0.32 long, 0.21 broad; mouth 0.04 broad.

_Habitat._--Central Pacific, Station 270, depth 2925 fathoms.



Subfamily 2. ARCHICAPSIDA, Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Cyrtocalpida#, with the basal mouth of the shell
fenestrated (vel Monocyrtida eradiata clausa).



Genus 532. _Halicapsa_,[149] Haeckel, 1881 Prodromus, p. 429.

_Definition._--#Archicapsida# with an apical horn.

The genus _Halicapsa_, and the following closely allied _Archicapsa_,
represent together the small subfamily of Archicapsida, or of those
Cyrtocalpida, in which the basal mouth of the simple shell is closed by a
lattice plate. This may be the original state of this family, if it is
derived from the Circospyrida (_Circospyris_, _Dictyospyris_) by loss of
the sagittal constriction and the primary ring. But it is also possible
that the Archicapsida have been partly derived from the Archicorida by
secondary fenestration of the open mouth. The genus _Halicapsa_ may be
easily confounded with the similar Ellipsid _Lithapium_ (compare p. 303,
Pl. 14, figs. 8-10). The skeleton of both genera may be perfectly similar,
the only distinction being the structure of the central capsule, which in
_Halicapsa_ is that of the MONOPYLEA, in _Lithapium_ that of the PERIPYLEA.



{1190}Subgenus 1. _Calpocapsa_, Haeckel.

_Definition._--Surface of the shell smooth or rough, but not spiny.


1. _Halicapsa lithapium_, n. sp. (Pl. 97, fig. 6).

Shell pear-shaped, rough, one and a half times as long as broad. Pores
subregular, circular, twice as broad as the bars. Basal plate with four
larger ovate cortinar pores (two larger cardinal and two smaller jugular),
and with six smaller peripheral pores (fig. 6). Horn of the apex
three-sided pyramidal, stout, half as long as the shell.

_Dimensions._--Shell 0.16 long, 0.1 broad; horn 0.08 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


2. _Halicapsa triglochin_, n. sp. (Pl. 53, figs. 3, 4).

Shell ovate, rough, a little longer than broad. Pores regular, circular,
hexagonally framed, of the same breadth as the bars. Basal plate (fig. 4)
without larger pores. Horn pyramidal, stout, about half as long as the
shell, with three short, horizontally divergent secondary spines at the
base (possibly remnants of three original cortinar feet?)

_Dimensions._--Shell 0.11 long, 0.09 broad; horn 0.06 long.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


3. _Halicapsa prunoides_, n. sp.

Shell pear-shaped, tuberculate, a little longer than broad. Pores
irregular, roundish, of different sizes. Basal plate with four larger and
six smaller pores. Horn pyramidal, stout, about one-third as long as the
shell. (May belong perhaps to the similar #Prunoidea# _Lithapium_, compare
p. 303 and Pl. 14, figs. 8-10.)

_Dimensions._--Shell 0.14 long, 0.12 broad; horn 0.05 long.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Echinocapsa_, Haeckel, 1881, Prodromus, p. 429.

_Definition._--Surface of the shell spiny, covered with thorns, papillæ or
larger spines.


4. _Halicapsa papillata_, n. sp.

Shell bottle-shaped, papillate, one and a half times as long as broad.
Pores circular, much larger in the middle part than towards the poles. The
elevated frames between them bear on the {1191}nodal points large blunt
conical papillæ. Basal plate without larger pores. Horn three-sided
pyramidal, one-third as long as the shell, gradually passing into the
slender neck of the bottle.

_Dimensions._--Shell 0.22 long, 0.15 broad; horn 0.07 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


5. _Halicapsa pyriformis_, Haeckel.

  ? _Haliomma pyriforme_, Bailey, 1856, Amer. Journ. Sci. and Arts, vol
  xxii. p. 1, pl. i. fig. 29.

Shell pear-shaped, a little longer than broad, covered with numerous short
conical spines. Pores subregular, circular, of nearly equal size, twice as
broad as the bars. Basal plate with four crossed larger ovate pores (two
larger cardinal and two smaller jugular pores). Horn stout pyramidal,
scarcely one-fourth as long as the shell.

_Dimensions._--Shell 0.16 long, 0.14 broad; horn 0.04 long.

_Habitat._--Fossil in Barbados, living in the North Pacific (Kamtschatka)?


6. _Halicapsa hystrix_, n. sp. (Pl. 53, figs. 5, 6).

Shell pear-shaped, subspherical, a little longer than broad, with scattered
stout pyramidal spines about as long as the radius of the shell. Pores
subregular, circular, three times as broad as the bars. Basal plate (fig.
6) without larger pores. Horn very large, pyramidal, longer than the shell.

_Dimensions._--Shell 0.1 long, 0.09 broad; horn 0.13 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



Genus 533. _Archicapsa_,[150] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archicapsida# without apical horn.

The genus _Archicapsa_ differs from the preceding _Halicapsa_ in the
absence of the apical horn, and represents the simplest form among the
Monocyrtida clausa, a simple, ovate, or pear-shaped shell without any
appendages. The characteristic structure of the basal lattice-plate (with
three or four large cortinar pores) makes it probable that _Archicapsa_ has
been derived either from _Halicapsa_, by loss of the horn, or directly from
_Dictyospyris_, by reduction of the sagittal ring and constriction.


1. _Archicapsa triforis_, n. sp. (Pl. 53, figs. 1, 2).

Shell pear-shaped, smooth, one and a half times as long as broad. Pores
subregular, circular, of about the same breadth as the bars. Basal plate
(fig. 2) with three very large pores, three times as broad as the others
(one odd sternal pore and two paired cardinal pores).

_Dimensions._--Shell 0.09 long, 0.06 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


{1192}2. _Archicapsa quadriforis_, n. sp.

Shell ovate, rough, a little longer than broad. Pores subregular, circular,
twice as broad as the bars. Basal plate with four larger ovate cortinar
pores (two smaller jugular and two larger cardinal pores).

_Dimensions._--Shell 0.12 to 0.15 long, 0.1 to 0.12 broad.

_Habitat._--Central Pacific, Station 265 to 268, depth 2700 to 2900
fathoms.


3. _Archicapsa nonaforis_, n. sp.

Shell pear-shaped, thorny, one and a half times as long as broad. Pores
regular, circular, small, hexagonally framed, twice as broad as the bars.
Basal plate with nine cortinar pores (three larger alternating with three
pairs of smaller pores, as in Pl. 87, fig. 2).

_Dimensions._--Shell 0.14 long, 0.09 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


----


Section II. DICYRTIDA, Haeckel, 1862, Monogr. d. Radiol., pp. 280, 296.

_Definition._--#Cyrtoidea# dithalamia, with two-jointed shell, being
divided by a transverse collar stricture into an apical joint (or cephalis)
and a basal joint (or thorax).

_Synopsis of the three Families and six Subfamilies of Dicyrtida._

  Family LXII. Tripocyrtida.  { Mouth open,    1. Sethopilida.
                              {
  Three radial apophyses.     { Mouth closed,  2. Sethoperida.

  Family LXIII. Anthocyrtida. { Mouth open,    3. Sethophormida.
                              {
  Numerous radial apophyses.  { Mouth closed,  4. Sethophænida.

  Family LXIV. Sethocyrtida.  { Mouth open,    5. Sethocorida.
                              {
  No radial apophyses.        { Mouth closed,  6. Sethocapsida.



Family LXII. #TRIPOCYRTIDA#, n. fam.

  _Sethopilida et Sethoperida_, Haeckel, 1881, Prodromus, pp. 431, 433.

_Definition._--#Dicyrtida# triradiata. (#Cyrtoidea# with a two-jointed
shell, divided by a transverse constriction into cephalis and thorax, and
bearing three radial apophyses.)

{1193}The family #Tripocyrtida#, composed of the Sethopilida and
Sethoperida of my Prodromus, comprises those #Cyrtoidea# in which the
lattice-shell is two-jointed and bears three radial apophyses. The two
subfamilies differ in the shape of the mouth, which in the Sethopilida is a
simple wide opening, but in the Sethoperida is closed by a lattice-plate;
the former are here divided into sixteen, the latter into eight different
genera. Though probably the two shell-joints are not truly homologous in
all Tripocyrtida, we call the first joint here, as in all Dicyrtida, the
cephalis, and the second joint the thorax.

Numerous Tripocyrtida, living as well as fossil forms, were formerly
described by Ehrenberg. His genera _Dictyophimus_, _Clathrocanium_,
_Lithomelissa_, and _Lychnocanium_ belong to the Sethopilida, and have the
mouth open; his genera _Lithopera_ and _Lithochytris_ (partly) belong to
the Sethoperida, and have the basal mouth closed by a lattice-plate. Many
of these Tripocyrtida belong probably to the oldest forms of Dicyrtida, are
nearly related to the Phormospyrida, and therefore of special phylogenetic
interest, as was demonstrated by Bütschli (1882, _loc. cit._, pp. 514-519).
This near relation to certain #Spyroidea# (_Tripospyris_, _Acrospyris_,
&c.) is particularly striking in some forms of _Clathrocanium_,
_Lithomelissa_, &c. Some other Tripocyrtida seem to possess a closer
relation to certain #Plectoidea# (_Plagoniscus_, _Plectaniscus_), so mainly
some forms of _Tripocyrtis_ and _Dictyophimus_.

The cephalis, or the first joint of the shell, corresponds usually to the
whole shell of the Zygospyrida and of numerous Monocyrtida, and exhibits
various modifications of shape, which have been already described in these
latter families. It is usually subspherical or hemispherical and armed with
an apical horn. In a small number of genera the horn is lost, in some other
genera multiplied. The cephalis is separated from the thorax not only
externally by the collar constriction, but commonly also internally by a
transverse horizontal fenestrated septum, which usually exhibits three or
four characteristic cortinar pores. The central capsule, originally
enclosed in the cephalis, develops usually three or four large pear-shaped
cæcal sacs which pass through the cortinar pores and depend into the thorax
(Pl. 55, figs. 2-11; Pl. 60, figs. 3-7, &c.).

The thorax in this family exhibits a great variety of interesting
modifications, mainly in the development of the three radial apophyses
arising from it. These may be either enclosed in the wall of the thorax as
ribs, or arise as free wings, very often prolonged over the mouth as three
terminal feet. Finally the three terminal feet only remain, whilst the
original ribs are lost. The special ornamentation of these three apophyses
exhibits an extraordinary variety and elegancy of structure, and many
Tripocyrtida belong, no doubt, to the most graceful and admirable forms of
NASSELLARIA.

{1194}_Synopsis of the Genera of Tripocyrtida._

  -------------------------------------------------------------------------
  I. Subfamily Sethopilida.
     Terminal mouth of the thorax a simple wide opening.
                            --------------------
  A. Three radial ribs (or cortinar rods) partly or completely enclosed in
     the wall of the thorax. No latticed vertical cephalic wings.
  -------------------------------------------------------------------------
  a. Three thoracic {               { Feet solid,    534. _Dictyophimus_.
   ribs prolonged   { Cephalis      {
   into three       {  with a horn. { Feet latticed, 535. _Tripocyrtis_.
   terminal feet.   {
                    { No horn, feet solid,           536. _Sethopilium_.

                    { Thorax        { With horn,     537. _Lithomelissa_.
                    {  perfectly    {
  b. Three thoracic {  latticed.    { No horn,       538. _Psilomelissa_.
   ribs prolonged   {
   into three       { Thorax with spongy framework,  539. _Spongomelissa_.
   lateral wings.   {
                    { Thorax with three large
                    {  lateral holes between
                    {  the three ribs,               540. _Clathrocanium_.

  c. Three thoracic {
   ribs completely  { Peristome simple, smooth,      541. _Lamprodiscus_.
   enclosed in the  {
   wall of the      { Peristome with a corona of
   flat thorax      {  spines,                       542. _Lampromitra_.
  -------------------------------------------------------------------------
  B. Three radial ribs enclosed in the wall of the thorax and connected
     with the cephalic horn by three latticed vertical wings.
  -------------------------------------------------------------------------
  a. Thorax         { No frontal horn (four spines), 543. _Callimitra_.
   completely       {
   latticed         { With frontal horn (five
                    {  spines),                      544. _Clathromitra_.

  b. Thorax with three large lateral holes between
   the three ribs. No frontal horn,                  545. _Clathrocorys_.
  -------------------------------------------------------------------------
  C. Three radial beams (or cortinar rods) perfectly free, not enclosed in
     the wall of the thorax.
  -------------------------------------------------------------------------
  Three beams outside the thorax, arising freely
   from the collar stricture (no cephalic hole),     546. _Eucecryphalus_.

  Three beams inside the thorax. Cephalis with
   a large apical hole,                              547. _Amphiplecta_.
  -------------------------------------------------------------------------
  D. Three radial terminal feet on the peristome (the three original
     lateral ribs are lost).
  -------------------------------------------------------------------------
  Feet solid,                                        548. _Lychnocanium_.

  Feet latticed,                                     549. _Lychnodictyum_.
  -------------------------------------------------------------------------
  II. Subfamily Sethoperida.
      Terminal mouth of the thorax closed by a lattice-plate.
                            --------------------
      Three divergent ribs (or cortinar rods) enclosed either in the wall
         or in the cavity of the thorax.
  -------------------------------------------------------------------------
  Three ribs enclosed in the lattice-wall of the
   thorax,                                           550. _Sethopera_.

  Three internal rods in the cavity of the thorax,   551. _Lithopera_.
  -------------------------------------------------------------------------
  Three divergent free lateral wings (as prolongation of the three ribs)
     on the sides of the thorax.
  -------------------------------------------------------------------------
  Three solid       { Cephalis with horn,            552. _Micromelissa_.
   lateral spines.  {
                    { No horn,                       553. _Peromelissa_.

  Three latticed lateral wings. With horn,           554. _Sethomelissa_.
  -------------------------------------------------------------------------
  Three free terminal feet (on the base of the thorax).
  -------------------------------------------------------------------------
  Three feet solid,                                  555. _Tetrahedrina_.

                    { Shell without external
  Three feet        {  mantle,                       556. _Sethochytris_.
   latticed.        {
                    { Shell with an arachnoidal
                    {  mantle,                       557. _Clathrolychnus_.



{1195}Subfamily 1. SETHOPILIDA, Haeckel, 1881, Prodromus, p. 431.

_Definition._--#Tripocyrtida#, with the basal mouth of the shell open (vel
Dicyrtida triradiata aperta).



Genus 534. _Dictyophimus_,[151] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 53.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
complete thoracic ribs, prolonged into three solid divergent feet on the
peristome. Cephalis with an apical horn.

The genus _Dictyophimus_, comprising many common species, may be regarded
as the common ancestral form of all sethopilida, and therefore also of the
whole family of Dicyrtida. The cephalis bears an apical horn, and the
thorax three ribs, which are prolonged over the open mouth into three solid
feet. _Dictyophimus_ may be derived either from _Euscenium_ or _Peridium_
(Archiperida), or from _Tripospyris_ (Zygospyrida), or from _Plectaniscus_
(Plectanida), by development of lattice-work between the three terminal
feet, which therefore become thoracic ribs.



Subgenus 1. _Dictyophimium_, Haeckel.

_Definition._--Shell smooth or rough, without prominent spines on the edges
of the three thoracic ribs. (Commonly one single horn on the cephalis.)


1. _Dictyophimus sphærocephalus_, n. sp. (Pl. 57, fig. 10).

Shell smooth, with a deep collar stricture, separating two joints of nearly
equal size. Cephalis subglobular, rough, with a stout pyramidal horn of
half the length, and regular, circular, hexagonally framed pores. Thorax
nearly three-sided prismatic, smooth, with three stout, little divergent or
nearly parallel ribs, which are prolonged into conical subvertical feet
half as long. Thoracic pores irregular, roundish.

_Dimensions._--Cephalis 0.08 long, 0.08 broad; thorax 0.08 long, 0.08
broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Dictyophimus_ tripus, Haeckel.

  _Dictyophimus tripus_, Haeckel, 1862, Monogr. d. Radiol., p. 306, Taf.
  vi. fig. 1.

Shell with a slight collar stricture, separating two joints of slightly
different size. Cephalis nearly ellipsoidal, large, with a slender conical
horn of the same length. Thorax truncate three-sided {1196}pyramidal, with
three strongly divergent ribs, which are prolonged into three slender
conical feet of about the same length. Pores irregular, roundish, of
variable size.

_Dimensions._--Cephalis 0.032 long, 0.028 broad; thorax 0.34 long, 0.064
broad.

_Habitat._--Mediterranean (Messina), Atlantic (Canary Islands), surface.


3. _Dictyophimus plectaniscus_, n. sp. (Pl. 61, figs. 8, 9).

Shell flat, pyramidal, smooth, with distinct collar stricture. Cephalis
hemispherical, with a conical horn of the same length and numerous small
regular pores. Thorax flat, triangular, pyramidal, with three widely
divergent ribs, which are prolonged into three cylindrical feet of the same
length. Thoracic pores fifteen, very large, subregular, roundish, disposed
in two transverse girdles, the inner with six, the outer with nine pores;
five pores between every two ribs.

_Dimensions._--Cephalis 0.04 long, 0.06 broad; thorax 0.08 long, 0.18
broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


4. _Dictyophimus craticula_, Ehrenberg.

  _Dictyophimus craticula_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. v. figs. 4, 5.

  _Dictyophimus craticula_, Bütschli, 1882, Zeitschr. f. Wiss. Zool., vol.
  xxxvi. p. 515, Taf. xxxiii. fig. 35.

Shell flat, pyramidal, very similar to the preceding species, but differing
in the rudimentary horn, which is smaller than half the cephalis, and in
the length of the three cylindrical feet, which are twice to three times as
long as the shell. The nine inferior large pores of the thorax are twice to
three times as large as the six superior pores. The basal peristome is
commonly thorny.

_Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.1 long, 0.2 broad.

_Habitat._--Fossil in Barbados.


5. _Dictyophimus pyramis_, n. sp. (Pl. 61, fig. 16).

Shell regular, pyramidal, with flat collar stricture. Relative length of
the two joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical, with a
stout pyramidal horn of the same length. Thorax triangular pyramidal, with
three prominent ribs, which are prolonged into three slender pyramidal
feet, half as long. Pores small and very numerous, subregular, circular.

_Dimensions._--Cephalis 0.03 long, 0.05 broad; thorax 0.1 long, 0.15 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


6. _Dictyophimus challengeri_, Haeckel.

  _Dictyophimus challengeri_, Haeckel, 1878, Protistenreich, p. 47, fig.
  35.

Shell campanulate, with sharp collar stricture. Relative length of the
joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a stout
pyramidal horn of twice the length, and numerous {1197}very small pores.
Thorax nearly hemispherical, with three vaulted bosoms between the three
decurrent ribs, which are prolonged into three nearly parallel and vertical
feet of about the same length. Pores subregular, circular, of medium size.
This species is very similar to _Lychnodictyum challengeri_, Haeckel, but
differs in the smaller straight horn and the longer solid feet, which are
not fenestrated.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.13
broad.

_Habitat._--Tropical Atlantic, Station 347, surface.


7. _Dictyophimus lasanum_, n. sp. (Pl. 61, fig. 5).

Shell nearly pear-shaped, with distinct collar stricture. Relative length
of the two joints = 1 : 3, breadth = 1 : 3. Cephalis hemispherical, with a
conical horn of the same length. Thorax nearly spherical, on both poles
truncate and constricted, with three decurrent curved ribs and small
regular circular pores. The prolongations of the ribs form three divergent
pyramidal straight feet, nearly as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.09
broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


8. _Dictyophimus longipes_, n. sp. (Pl. 61, fig. 3).

Shell three-sided pyramidal, with distinct collar stricture. Relative
length of the two joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical,
with a rudimentary pyramidal horn, scarcely one-fourth as long; and with
small circular regular pores. Thorax with larger irregular pores, and three
vaulted bosoms between the three decurrent ribs, which are prolonged into
three very long and slender prismatic feet, S-shaped, curved, and twice to
three times as long as the shell.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.13
broad.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


9. _Dictyophimus gracilipes_, Bailey.

  _Dictyophimus gracilipes_, Bailey, 1856, Amer. Journ. Sci. and Arts, vol.
  xxii. p. 4, pl. i. fig. 8.

Shell three-sided pyramidal, with a deep collar stricture. Relative length
of the two joints = 1 : 3, breadth = 1 : 4. Cephalis hemispherical, with a
thin horn of the same length. Thorax with three curved ribs, which are
prolonged into three divergent angular feet of the same length. Pores
irregular roundish.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.05 long, 0.08
broad.

_Habitat._--North Pacific, Station 240, surface, Kamtschatka (Bailey).


10. _Dictyophimus cortina_, n. sp. (Pl. 61, fig. 1).

Shell three-sided pyramidal, with distinct collar stricture. Relative
length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical,
with a pyramidal horn of half the length. Thorax {1198}with much larger
irregular roundish pores and three prominent ribs, which are prolonged into
three stout, club-shaped, strongly divergent feet of the same length. Mouth
widely open, elegantly coronate, with a circle of numerous small cilia.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


11. _Dictyophimus arabicus_, Haeckel.

  _Lychnocanium arabicum_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 296, Taf. x. fig. 3.

Shell smooth, three-sided pyramidal, with deep collar stricture. Relative
length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical,
with a slender horn of the same length. Thorax with much larger, irregular
roundish pores, and three widely divergent ribs, which are prolonged into
three slender, somewhat recurved feet of about the same length.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.07 long, 0.09
broad.

_Habitat._--Indian Ocean, Zanzibar (Pullen), depth 2200 fathoms.


12. _Dictyophimus platycephalus_, n. sp. (Pl. 60, figs. 4, 5).

Shell smooth, flat, three-sided pyramidal, with distinct collar stricture.
Relative length of the two joints = 1 : 3, breadth = 3 : 9. Cephalis flat,
cap-shaped, three times as broad as long, with a slender conical horn of
the same length. Thorax flatly vaulted, with much larger, irregular
roundish, double-edged pores, and three widely divergent ribs, which are
prolonged into three slender conical feet of the same length. Central
capsule in the cephalis flat, discoidal, with a discoidal nucleus of half
the size, and with four large pear-shaped cæcal sacs depending into the
thorax, each of which contains a large oil globule (fig. 4).

_Dimensions._--Cephalis 0.02 long, 0.07 broad; thorax 0.06 long, 0.18
broad.

_Habitat._--North Atlantic, Canary Islands (Lanzerote), Haeckel, surface.


13. _Dictyophimus brandtii_, n. sp. (Pl. 60, fig. 6).

Shell smooth, flat, three-sided pyramidal, with deep collar stricture, very
similar to the preceding species. Relative length of the two joints =
1 : 3, breadth = 2 : 7. Cephalis hemispherical, with a slender conical horn
of twice the length. Thorax flatly vaulted, with irregular polygonal pores
and thin bars; and with three widely divergent ribs, which are prolonged
into three slender prismatic feet of thrice the length. In fig. 6 the shell
is seen from the base and exhibits very distinctly the collar septum with
its four large meshes, two minor jugular and two major cardinal pores.

_Dimensions._--Cephalis 0.03 long, 0.07 broad; thorax 0.08 long, 0.2 broad.

_Habitat._--North Pacific, Station 236, surface.


{1199}14. _Dictyophimus lucerna_, Haeckel.

  _Lychnocanium lucerna_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 6;
  Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 80, Taf. viii. fig. 3.

  _Lychnocanium lucerna_, Haeckel, 1862, Monogr. d. Radiol., p. 311.

Shell smooth, three-sided pyramidal, with slight collar stricture. Relative
length of the two joints = 1 : 4, breadth = 1 : 4. Cephalis hemispherical,
with a thick conical horn of twice the length. Thorax with small regular,
circular pores and three flat sides; between these arise three rounded
ribs, which are prolonged into three short, conical, divergent feet,
one-third as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.025 broad; thorax 0.08 long, 0.08
broad.

_Habitat._--Fossil in Barbados.


15. _Dictyophimus hamosus_, Haeckel.

  _Lychnocanium hamosum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. vii. fig. 9.

Shell pear-shaped, rough, with deep collar stricture. Relative length of
the two joints = 1 : 2, breadth = 1 : 3. Cephalis subglobular, with a
conical horn of twice the length. Thorax with small, regular, circular
pores, and with three prominent ribs, prolonged into three vertical
prismatic feet, which are about as long as the shell, parallel or a little
convergent towards the distal end, with recurved teeth or hooks at the
lateral edges.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.04 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


16. _Dictyophimus tridentatus_, Haeckel.

  _Lychnocanium tridentatum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 80, Taf. vii. fig. 4.

Shell smooth, three-sided pyramidal, with deep collar stricture. Relative
length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical,
with a conical horn of the same length, and some small accessory thorns.
Thorax tetrahedral, with three smooth hyaline walls, bearing only a single
series of small pores on each side of the three prominent ribs, which are
prolonged into three strong prismatic curved feet of twice the length, with
the convexity external. A group of small pores and a strong triangular
tooth at the base of each foot.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.08
broad.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Lamprotripus_, Haeckel, 1881, Prodromus, p. 432.

_Definition._--Shell spiny or thorny, with prominent spines on the edges of
the three thoracic ribs. (Commonly one larger and a few smaller horns or
spines on the cephalis.)


{1200}17. _Dictyophimus triserratus_, n. sp. (Pl. 61, fig. 17).

Shell three-sided pyramidal, with slight collar stricture. Relative length
of the two joints = 1 : 3, breadth = 1 : 4. Cephalis small, subspherical,
with a large pyramidal horn three times as long. Thorax with much larger,
irregular roundish, double-edged pores, and three prominent, serrate ribs,
which are prolonged into three pyramidal strongly divergent feet of the
same length.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.09
broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


18. _Dictyophimus bicornis_, n. sp.

Shell thorny, with deep collar stricture. Relative length of the two joints
= 2 : 3, breadth = 2 : 3. Cephalis nearly as large as the thorax,
subglobular, with numerous small, circular pores, and two divergent
pyramidal horns of half the length (a major occipital and a minor frontal
horn). Thorax three-sided pyramidal, with larger irregular pores and three
serrate ribs, which are prolonged into three prismatic spiny feet of half
the length. (Differs from the similar _Dictyophimus sphærocephalus_, Pl.
57, fig. 10, mainly in the double horn and the spinulate feet.)

_Dimensions._--Cephalis 0.05 long, 0.05 broad; thorax 0.08 long, 0.07
broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


19. _Dictyophimus pocillum_, Ehrenberg.

  _Dictyophimus pocillum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. v. fig. 6.

Shell thorny, with distinct collar stricture. Relative length of the two
joints = 1 : 5, breadth = 1 : 5. Cephalis nearly spherical, with numerous
small conical spines. Thorax flat, three-sided pyramidal with large,
irregular, roundish pores, and three strong, widely divergent, spinulate
ribs, which are prolonged into three prismatic spinulate feet of the same
length.

_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.15 long, 0.15
broad.

_Habitat._--Fossil in Barbados.


20. _Dictyophimus cienkowskii_, n. sp. (Pl. 60, fig. 1).

  _Lamprotripus squarrosus_, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal, with slight collar stricture. Relative
length of the two joints = 1 : 3, breadth = 2 : 6. Cephalis flat,
cap-shaped, three times as long as broad, with numerous bristle-shaped
spines three times as long. Thorax also spiny, with irregular, very large,
polygonal meshes and thin bars; its three ribs prolonged into three very
long and thin, widely divergent, prismatic feet, bearing numerous long
spines on the three edges.

_Dimensions._--Cephalis 0.025 long, 0.05 broad; thorax 0.075 long, 0.15
broad.

_Habitat._--North Pacific, Station 250, surface.


{1201}21. _Dictyophimus bütschlii_, n. sp. (Pl. 60, fig. 2).

  _Lamprotripus horridus_, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal, with deep collar stricture. Relative length
at the two joints = 1 : 2, breadth = 1 : 5. Cephalis subspherical, with
numerous long, bristle-shaped spines and a larger ramified horn. Thorax
also spiny, flatly vaulted, with large, subregular, hexagonal meshes and
thin bars; its three spiny ribs prolonged into three very long and thin,
prismatic, widely divergent feet, twice to four times as long as the
thorax.

_Dimensions._--Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

_Habitat._--South Pacific, Station 284, surface.


22. _Dictyophimus hertwigii_, n. sp. (Pl. 60, fig. 3).

  _Lamprotripus spinosus_, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal with sharp collar stricture. Relative length
of the two joints = 1 : 2, breath = 1 : 5. Cephalis subspherical, with
irregular roundish pores, numerous small spines and a large, oblique,
prismatic horn of the same length, bearing on its distal end a bunch of
small divergent spines. Thorax pyramidal, with larger irregular polygonal
pores and thin bars; its three strong, widely divergent ribs spiny,
straight, and prolonged into three prismatic slender feet of the same
length. Central capsule with three lobes depending into the thorax.

_Dimensions._--Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

_Habitat._--Central Pacific, Stations 270 to 274, surface.



Genus 535. _Tripocyrtis_,[152] n. gen.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
complete thoracic ribs, prolonged into three latticed divergent feet on the
peristome. Cephalis with an apical horn.

The genus _Tripocyrtis_ has been derived from the preceding _Dictyophimus_
by complete fenestration of the three basal feet, which throughout their
whole length become united by complete lattice-work. This genus is closely
allied to _Plectaniscus_.


1. _Tripocyrtis plagoniscus_, n. sp. (Pl. 60, fig. 10).

Cephalis subspherical, with large, roundish meshes and a stout, three-sided
pyramidal, irregularly branched horn of twice the length. Thorax with a
small number of large, irregular, polygonal meshes and three stout curved
ribs about as long as the cephalic horn.

_Dimensions._--Cephalis 0.06 long, 0.07 broad; thorax 0.11 long, 0.16
broad.

_Habitat._--Central Pacific, Station 266, surface.


{1202}2. _Tripocyrtis tripodiscus_, n. sp.

Cephalis subspherical, with small, polygonal pores and a large,
arborescent, vertical horn of thrice the length, bearing numerous ramified
branches. Thorax with three straight, widely divergent ribs, of the same
length as the horn, connected by a delicate, arachnoidal framework with
irregular, polygonal meshes.

_Dimensions._--Cephalis 0.04 long, 05 broad; thorax 0.12 long, 0.18 broad.

_Habitat._--Central Pacific, Station 269, surface.


3. _Tripocyrtis plectaniscus_, n. sp. (Pl. 60, fig. 9).

Cephalis subspherical, with small roundish pores, and a stout, three-sided
pyramidal, denticulate horn of the same length. Thorax with three little
divergent and curved ribs, twice as long as the horn, in the upper half
with smaller, in the lower half with larger, polygonal, irregular meshes.

_Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.1 long, 0.12 broad.

_Habitat._--Central Pacific, Station 264, surface.



Genus 536. _Sethopilium_,[153] Haeckel, 1881, Prodromus, p. 431.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
complete thoracic ribs, which are prolonged into three solid divergent feet
on the peristome. Cephalis smooth, without a horn.

The genus _Sethopilium_ differs from its probable ancestral form
_Dictyophimus_ by the complete loss of the cephalic horn, and of the collar
septum between both joints, which are only separated by the slight external
collar stricture.


1. _Sethopilium orthopus_, n. sp. (Pl. 97, fig. 8).

Shell smooth, with sharp collar stricture, Relative length of the two
joints = 5 : 4, breadth = 7 : 6. Cephalis large, subspherical, with
numerous regular circular pores, twice as broad as the bars. Thorax with
three stout, straight, widely divergent ribs, prolonged into three straight
pointed feet of the same length. Between every two ribs, in the centre of
the collar stricture, a single large triangular mesh, and beyond this three
to six rows of smaller irregular meshes.

_Dimensions._--Cephalis 0.05 long, 0.07 broad; thorax 0.04 long, 0.06
broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Sethopilium cyrtopus_, n. sp.

Shell smooth, with sharp collar stricture.  Relative length of the two
joints = 4 : 6, breadth = 7 : 11. Cephalis hemispherical, with large
irregular roundish pores, four times as broad as the bars. {1203}Thorax
with three stout, curved, widely divergent ribs, prolonged into three
cylindro-conical, curved feet of twice the length, which are convex in the
proximal half, concave in the distal half. Between every two ribs, beyond
the collar stricture, two large ovate meshes, and beyond this two rows of
smaller irregular meshes.

_Dimensions._--Cephalis 0.04 long, 0.07 broad; thorax 0.05 long, 0.11
broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Sethopilium macropus_, n. sp. (Pl. 97, fig. 9).

Shell smooth, with slight collar stricture. Relative length of the two
joints = 4 : 7, breadth = 6 : 13. Cephalis hemispherical, with irregular
double-contoured pores, about as broad as the bars. Thorax with three very
stout, carved, widely divergent ribs, prolonged into three curved,
cylindrical, very long feet, which are three to four times as long as the
shell, and convex on the outside. Between every two ribs, beyond the collar
stricture, two large broad meshes, and beyond this two or three rows of
smaller meshes.

_Dimensions._--Cephalis 0.04 long, 0.06 broad; thorax 0.07 long, 0.13
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 537. _Lithomelissa_,[154] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
free lateral wings, or solid spines arising from the sides of the thorax.
No terminal feet. Cephalis with one or more horns.

The genus _Lithomelissa_, containing numerous and widely distributed forms,
may like _Dictyophimus_ be regarded as one of the most primitive and
ancient forms of Dicyrtida. It differs from the latter by the lateral (not
terminal) position of the three thoracic feet, and may be derived either
from _Dictyophimus_ (by secondary development of intrapedal network towards
the mouth, on the inside of the three feet) or directly from _Tripospyris_
by similar formation of thoracic network beyond the collar stricture,
outside the base of the three divergent feet and pierced by the latter. As
the species of this genus are numerous, it may perhaps be better to divide
it into two or three genera: _Acromelissa_, with a single horn,
_Micromelissa_, with two horns, and _Sethomelissa_, with three or more
horns.



Subgenus 1. _Acromelissa_, Haeckel, 1881, Prodromus, p. 431.

_Definition._--Cephalis with a single occipital horn.


{1204}1. _Lithomelissa macroptera_, Ehrenberg.

  _Lithomelissa macroptera_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. iii. figs. 9, 10.

Shell smooth, with distinct collar stricture. Relative length of the two
joints = 4 : 5, breadth = 3 : 4. Cephalis ovate, with a stout, excentric,
vertical, pyramidal horn of the same length. Thorax little larger, ovate,
truncate. Both joints with very small and scattered pores. Three divergent
ribs arise from the base of the cephalic horn, and are prolonged over the
major part of the thorax; their under free part arises from the middle part
of the thorax and is as long as the horn, straight, pyramidal. Mouth
truncate, little constricted.

_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax 0.05 long, 0.04
broad.

_Habitat._--Fossil in Barbados.


2. _Lithomelissa ehrenbergii_, Bütschli.

  _Lithomelissa ehrenbergii_, Bütschli, 1882, Zeitschr. f. wiss. Zool.,
  vol. xxxvi. p. 517, Taf. xxxiii. fig. 21_a_, _b_.

  _Lithomelissa macroptera_, var., Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 78, Taf. iii. fig. 8.

  (?) _Lophophæna capito_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. viii. fig. 6.

  (?) _Lophophæna galeata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. viii. fig. 12.

Shell rough, with distinct collar stricture. Relative length of the two
joints = 4 : 2, breadth = 3 : 4. Cephalis ovate, with a stout excentric,
oblique, pyramidal horn of half the length. Thorax little shorter,
truncate, conical. Both joints with regular circular pores, of the same
breadth as the bars. Three divergent conical feet, as long as the cephalis,
arise below the collar stricture. Mouth truncate, not constricted.

_Dimensions._--Cephalis 0.08 long, 0.06 broad; thorax 0.04 long, 0.08
broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; fossil in
Barbados.


3. _Lithomelissa macroceras_, n. sp.

Shell spiny, with sharp collar stricture. Relative length of the two joints
= 5 : 7, breadth = 5 : 6. Cephalis spherical, with a large pyramidal horn
of twice the length. Thorax little longer, ovate, truncate. Both joints
with regular circular pores, three times as broad as the bars. Three
divergent pyramidal feet, twice as long as the cephalis, arise from the
middle part of the thorax. Mouth constricted, half as broad as the thorax.

_Dimensions._--Cephalis 0.05 long, 0.05 broad; thorax 0.07 long, 0.06
broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


4. _Lithomelissa mitra_, Bütschli.

  _Lithomelissa mitra_, Bütschli, 1881, Zeitschr. f. wiss. Zool., p. 518,
  Taf. xxxiii. fig. 24.

Shell smooth, with distinct collar stricture. Relative length of the two
joints = 5 : 4, breadth = 4 : 5. Cephalis ovate, with a slender, straight,
vertical, pyramidal horn of the same length. Thorax ovate, {1205}truncate,
of about the same size. Both joints with very small and numerous pores, as
broad as the bars. Three feet arising from the middle part of the thorax,
very small, rudimentary, pyramidal, about as long as broad. Mouth truncate,
little constricted.

_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.04 long, 0.05
broad.

_Habitat._--Fossil in Barbados.


5. _Lithomelissa pycnoptera_, n. sp.

Shell rough, papillate, with slight collar stricture. Relative length of
the two joints = 1 : 3, breadth = 1 : 3. Cephalis small, hemispherical,
with very small pores and a slender, straight, conical horn of twice the
length. Thorax subconical, with regular circular, hexagonally framed pores,
as broad as the bars. From its lower half arise three divergent, very
strong feet, pyramidal, as long as the thorax, and three times as long as
broad.

_Dimensions._--Cephalis 0.03 diameter, thorax 0.1 diameter.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


6. _Lithomelissa microstoma_, n. sp.

Shell papillate, with slight collar stricture. Relative length of the two
joints = 1 : 5, breadth = 1 : 5. Cephalis small, hemispherical, with a
conical horn of twice the length. Thorax subspherical, with subregular
circular pores, three times as broad as the bars. From its middle part
arise three divergent, stout, conical feet, of half the length, and twice
as long as broad. Mouth small, strongly constricted, one-fourth to
one-third as broad as the thorax.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.15 diameter.

_Habitat._--Fossil in Barbados.


7. _Lithomelissa amphora_, Stöhr.

  _Lithomelissa amphora_, Stöhr, 1880, Palæontograph, vol. xxvi. p. 100,
  Taf. iii. fig. 11.

Shell smooth, with sharp collar stricture. Relative length of the two
joints = 1 : 5, breadth = 2 : 4. Cephalis small, hemispherical, with a
cervical horn of the same length. Thorax ovate, with small regular circular
pores, twice as broad as the bars. From its upper half arise three
divergent, slender, conical feet, only one-fourth as long. Mouth
constricted, with a hyaline peristome, half as broad as the thorax.

_Dimensions._--Cephalis 0.013 long, 0.026 broad; thorax 0.063 long, 0.053
broad.

_Habitat._--Fossil in tertiary rocks of Sicily; Grotte (Stöhr).



Subgenus 2. _Micromelissa_, Haeckel, 1881, Prodromus, p. 433 (_sensu
emendato_).

_Definition._--Cephalis with two divergent horns, a superior occipital horn
and an inferior frontal horn.


{1206}8. _Lithomelissa thoracites_, Haeckel.

  _Lithomelissa thoracites_, Haeckel, 1862, Monogr. d. Radiol., p. 301,
  Taf. vi. figs. 2-8.

  _Lithomelissa thoracites_, R. Hertwig, 1879, Organism. d. Radiol., p. 76,
  Taf. viii. fig. 1.

Shell smooth, with deep collar stricture. Cephalis ovate, with two
divergent, slender, conical horns, of about half the length; a major
oblique occipital horn on the posterior face, and a minor, nearly
horizontal horn above the collar stricture, on the anterior face. Thorax
about as large as the cephalis, truncate, ovate. Pores of both joints
irregular, roundish, of different sizes. From the upper half of the thorax,
below the collar stricture, there arise three slender, conical divergent
feet, about as long as the cephalis. Mouth truncate, wide open, not
constricted. On the numerous varieties of this common species compare my
Monograph, on the structure of the ovate central capsule (enclosed in the
cephalis), Hertwig, _loc. cit._

_Dimensions._--Cephalis 0.05 to 0.08 long, 0.04 broad; thorax 0.03 to 0.05
long, 0.05 to 0.07 broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific,
surface.


9. _Lithomelissa mediterranea_, J. Müller.

  _Lithomelissa mediterranea_, J. Müller, 1858, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 45, Taf. vi. fig. 11.

  _Lithomelissa mediterranea_, Haeckel, 1862, Monogr. d. Radiol., p. 302.

Shell smooth, with sharp collar stricture. Relative length of the two
joints = 4 : 5, breadth = 4 : 5. Cephalis campanulate, conical, with two
divergent small conical horns, a major occipital subvertical horn near the
summit, and a minor sub-horizontal frontal horn near the collar stricture.
Thorax truncate, ovate, little larger than the cephalis. From its lower
part there arise three short conical, divergent feet, scarcely half as long
as the cephalis (in Müller's figure one of them is seen shortened, opposite
to the frontal horn). Pores irregular, roundish, much smaller in the
cephalis than in the thorax.  Mouth wide open, not constricted.

_Dimensions._--Cephalis 0.04 diameter, thorax 0.05 diameter.

_Habitat._--Mediterranean (French shore), J. Müller, surface.


10. _Lithomelissa bicornis_, Ehrenberg.

  _Lithomelissa bicornis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 297, Taf. ii. fig. 7.

Shell smooth, with deep collar stricture. Relative length of the two joints
= 1 : 3, breadth = 1 : 2. Cephalis hemispherical, with two divergent, stout
and straight, pyramidal horns; a larger occipital horn sub-vertical near
the summit, and a smaller oblique frontal horn near the collar stricture.
Thorax subspherical, twice as large, with larger irregular, roundish pores.
From its lower half there arise three divergent curved pyramidal feet of
about the same length. Mouth constricted, only one-third as broad as the
thorax.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 diameter.

_Habitat._--Atlantic, Stations 348 to 353, surface.


{1207}11. _Lithomelissa haeckelii_, Bütschli.

  _Lithomelissa haeckelii_, Bütschli, 1883, Zeitschr. f. wiss. Zool., vol.
  xxxvi. p. 517, Taf. xxxiii. fig. 23, a, b.

Shell rough, with sharp collar stricture. Relative length of the two joints
= 6 : 5, breadth = 6 : 7. Cephalis subspherical, large, with two divergent
horns, a very large, oblique pyramidal occipital horn on the summit, and a
very small frontal horn on the middle of the forehead. Thorax campanulate,
little larger than the cephalis, with regular circular pores of twice the
breadth. From the upper part of the thorax, below the collar stricture,
there arise three stout, divergent, angular, semi-lunar feet, about as long
as the shell. Mouth wide open, not constricted.

_Dimensions._--Cephalis 0.6 long, 0.6 broad; thorax 0.05 long, 0.07 broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2260 fathoms; fossil in
Barbados.


12. _Lithomelissa bütschlii_, n. sp. (Pl. 56, fig. 1).

Shell smooth, with slight collar stricture. Relative length of the two
joints = 5 : 6, breadth = 4 : 5. Cephalis ovate, large, with two small
conical horns, which are opposed nearly horizontally, in the upper part of
the cephalis; an anterior frontal and a posterior occipital horn. Thorax
ovate, truncate, little larger. Pores of both joints irregular, roundish,
of very different sizes. From the middle part of the thorax there arise
three short conical divergent feet. (In the figured specimen there were
some accessory thorns; in another specimen, found afterwards, the surface
was quite smooth, but the two horns and the three feet much larger, half as
long as the cephalis.)

_Dimensions._--Cephalis 0.05 long, 0.04 broad; 0.06 long, 0.05 broad.

_Habitat._--Central Pacific, Stations 266 to 274, depth 2350 to 2925
fathoms.



Subgenus 3. _Sethomelissa_, Haeckel, 1881, Prodromus, p. 431.

_Definition._--Cephalis with three, four, or more horns, a primary
occipital, a secondary frontal, and one or more accessory parietal horns.


13. _Lithomelissa corythium_, Ehrenberg.

  _Lithomelissa corythium_, Ehrenberg, 1875, Abhandl. d.k. Akad. d. Wiss.
  Berlin, p. 78, Taf. iii, fig. 12.

Shell smooth, with slight collar stricture. Relative length of the two
joints = 4 : 3, breadth = 4 : 5. Cephalis campanulate, with three short
conical horns on the summit. Thorax flat and wide. From its upper part
below the collar stricture, there arise three divergent, pyramidal feet,
fenestrated at the base, about as long as the shell. Mouth wide open. (The
specimen figured by Ehrenberg was an incomplete one.)

_Dimensions._--Cephalis 0.04 in diameter, thorax 0.03 long, 0.05 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms; fossil in
Barbados.


{1208}14. _Lithomelissa decacantha_, n. sp. (Pl. 56, fig. 2).

  _Sethomelissa decacantha_, Haeckel, 1881, Prodromus et Atlas.

Shell smooth, with deep collar stricture, and with ten prismatic spines of
nearly equal size and similar form. Relative length and breadth of the two
joints about equal. Cephalis ovate, in the upper half hyaline, in the lower
half with few scattered pores; in the equator with four prismatic horns of
the same length, which diverge upwards; three of them are placed in the
same meridional planes as the three wings and the three feet of the thorax
(one occipital and two parietal); the fourth (frontal) horn is opposed to
the occipital. Thorax campanulate, three-edged, with three vertical
prominent feet (directed downward) and three horizontal wings, arising from
their knees. Mouth wide open, not constricted.

_Dimensions._--Cephalis 0.05 diameter; thorax 0.05 long, 0.06 broad.

_Habitat._--Equatorial Atlantic, Station 347, surface.



Genus 538. _Psilomelissa_,[155] Haeckel, 1881, Prodromus, p. 431.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
free lateral wings, or solid spines arising from the sides of the thorax.
No terminal feet. Cephalis smooth, without a horn.

The genus _Psilomelissa_ has the same formation of the shell as the nearly
allied preceding genus _Lithomelissa_, and may be derived from it by
reduction and loss of the cephalic horn. The cephalis is quite bare.


1. _Psilomelissa galeata_, Haeckel.

  _Dictyocephalus galeatus_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 289, Taf. vii. fig. 25.

Shell smooth, with sharp collar stricture. Relative length of the two
joints = 5 : 3, breadth = 4 : 5. Cephalis ovate, with numerous irregular,
roundish pores. Thorax truncate, conical, with a few small pores. From its
upper part (below the collar stricture) there arise three thin,
bristle-shaped, widely divergent wings, about as long as the cephalis.
Mouth widely open.

_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.03 long, 0.05
broad.

_Habitat._--Western Tropical Pacific, Stations 200 to 225, surface.


2. _Psilomelissa phalacra_, n. sp.

Shell smooth, with deep collar stricture. Relative length of the two joints
= 5 : 6, breadth = 4 : 4. Cephalis ovate, hyaline, with few small pores
only in the lower third. Thorax cylindrical, truncate, with small
irregular, roundish pores. From its upper third there arise below the
stricture three {1209}club-shaped, nearly horizontally divergent wings, as
long as the thorax. The cephalis and the three feet are similar to those of
_Peromelissa phalacra_, (Pl. 57, fig. 11); but the cylindrical thorax with
irregularly scattered pores is completely different, and exhibits a
truncate, wide open mouth.

_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.04
broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


3. _Psilomelissa hertwigii_, Haeckel.

  _Lithomelissa hertwigii_, Bütschli, 1882, Zeitschr. f. wiss. Zool., p.
  517, Taf xxxiii. fig. 22, _a_, _b_.

Shell rough, with obliterated collar stricture. Length of the two joints =
4 : 4, breadth = 5 : 5. Cephalis hemispherical. Thorax little larger,
cylindrical. From its upper half there arise three very strong pyramidal
divergent wings, about as long as the shell. Pores of both joints very
small and numerous, circular. Mouth truncate, wide open.

_Dimensions._--Cephalis 0.04 long, 0.06 broad; thorax 0.04 long, 0.05
broad.

_Habitat._--Fossil in Barbados.


4. _Psilomelissa calvata_, n. sp. (Pl. 56, fig. 3).

Shell smooth, with sharp collar stricture. Length of the two joints =
7 : 5, breadth = 5 : 6. Cephalis ovate, large, with subregular, circular,
double-contoured pores. Thorax smaller, ovate, with very irregular,
roundish pores of different sizes. From its upper third there arise three
conical, slender, widely divergent spines or wings of the same length. (In
fig. 3 the cephalis with the three wings is alone represented.)

_Dimensions._--Cephalis 0.07 long, 0.05 broad; thorax 0.05 long, 0.06
broad.

_Habitat._--Central Pacific, Stations 263 to 274, depth 2350 to 2925
fathoms.


5. _Psilomelissa sphærocephala_, n. sp.

Shell rough, with deep collar stricture. Length of the two joints = 1 : 2,
breadth = 1 : 3. Cephalis spherical. Thorax cap-shaped, flat and broad.
From its upper half there arise three pyramidal wings, half as long,
fenestrated at the base and nearly horizontally divergent. Mouth
constricted, half as broad as the thorax.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.06 long, 0.09 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 539. _Spongomelissa_,[156] n. gen.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
free lateral wings, or solid spines arising from the sides of the thorax.
No terminal feet. Cephalis with one or more horns.

{1210}The genus _Spongomelissa_ differs from its ancestral genus
_Lithomelissa_ only in the development of spongy framework in the
shell-wall--a very rare production in the #Cyrtoidea# (compare
_Peripyramis_, p. 1162, and _Spongocyrtis_, p. 1188).


1. _Spongomelissa spongiosa_, Haeckel.

  _Lithomelissa spongiosa_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. pp. 519, 539, Taf. xxxiii. fig. 25, _a_, _b_, _c_.

Shell of dense spongy structure, with a deep collar stricture. The
subspherical cephalis and the truncate abdomen of nearly equal size, both
with irregular delicate spongy framework. Mouth wide open. Cephalis with a
large vertical apical and a small oblique frontal horn. Thorax with three
very stout, three-sided prismatic widely divergent lateral wings, which are
covered with numerous irregularly ramified branches; the spongy framework
arises by communication of the delicate branches.

_Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.04 long, 0.06
broad.

_Habitat._--Fossil in Barbados.



Genus 540. _Clathrocanium_,[157] Ehrenberg, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 829.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
prominent lateral ribs on the thorax, alternating with three large holes
(or thoracic gates). Cephalis with a horn.

The genus _Clathrocanium_ is nearly allied to _Dictyophimus_ and
_Lithomelissa_, and, together with these two genera, may be regarded as
surviving representatives of the oldest and most primitive forms of
Dicyrtida. It differs from the latter mainly in the incomplete fenestration
of the shell, three large interradial holes remaining between the three
perradial thoracic ribs. It may therefore be derived either from
_Euscenium_ or from _Tripospyris_ by the development of a terminal
lattice-band between the three feet. _Clathrocanium_ may be divided into
two different subgenera: _Clathrocanidium_, with simple horn and smooth
mouth, and _Clathrocorona_, with fenestrated horn and coronated mouth.



Subgenus 1. _Clathrocanidium_, Haeckel.

_Definition._--Horn of the cephalis simple, not fenestrated. Peristome
smooth.


{1211}1. _Clathrocanium squarrosum_, Ehrenberg.

  _Clathrocanium squarrosum_, Ehrenberg, 1872, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 287, Taf. vii. fig. 5.

Cephalis campanulate, with irregular roundish pores and a pyramidal horn of
the same length, bearing at the apex three short branches. Length of the
two joints 2 : 3, breadth = 2 : 6. Thorax with three simple, prismatic,
thin ribs, which are twice as long as the cephalis, separated by large
triangular holes and connected only at the distal end by a small triangular
ring of delicate lattice-work. Peristome smooth, wide, as broad as the
thorax.

_Dimensions._--Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.12
broad.

_Habitat._--Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.


2. _Clathrocanium sphærocephalum_, n. sp. (Pl. 64, fig. 1).

Cephalis spherical, with regular circular pores and a prismatic horn of the
same length, with three serrated edges. Length of the two joints = 2 : 3,
breadth 2 : 4. Thorax with three broad, triangular, latticed, divergent
ribs, which are separated by three large ovate holes (about as large as the
cephalis), and connected at the distal end by a broad fenestrated circular
ring of regular lattice-work (about six pores in its height). Peristome
smooth, constricted, half as broad as the thorax.

_Dimensions._--Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.08
broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


3. _Clathrocanium coarctatum_, Ehrenberg.

  _Clathrocanium coarctatum_, Ehrenberg, 1872, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 287, Taf vii. fig. 6.

  _Lychnocanium fenestratum_, Ehrenberg, 1860, Monatsber. d. k. preuss.
  Akad. d. Wiss. Berlin, p. 767.

Cephalis spherical, thorny, with regular circular pores and a simple
pyramidal horn of the same length. Length of the two joints = 2 : 3,
breadth = 2 : 5. Thorax with three simple, prismatic, little prominent
ribs, which are separated by three large ovate holes (twice as long as the
cephalis), and connected below the prominent distal end by a narrow
circular ring of delicate lattice-work. Peristome smooth, wide, little
narrower than the thorax.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.06 long, 0.1 broad.

_Habitat._--Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.


4. _Clathrocanium triomma_, n. sp. (Pl. 64, fig. 3).

Cephalis spherical, thorny, with regular circular pores, and a slender
prismatic horn of twice the length, bearing at its apex three short
recurved branches. Length of the two joints = 2 : 4, breadth = 2 : 5.
Thorax with three broad prismatic, fenestrated ribs, which are separated by
three large {1212}subcircular holes, and below the prominent distal end by
a broad, triangular, roundish ring of subregular lattice-work (with square
pores). Peristome smooth, about half as broad as the thorax.

_Dimensions._--Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.1 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Subgenus 2. _Clathrocorona_, Haeckel, 1881, Prodromus, p. 431.

_Definition._--Horn of the cephalis fenestrated. Peristome on the margin of
the basal mouth with a corona of spines.


5. _Clathrocanium diadema_, n. sp. (Pl. 64, fig. 2).

  _Clathrocorona diadema_, Haeckel, 1881, Prodromus, p. 431.

Cephalis hemispherical, thorny, with irregular roundish pores, and a large
prismatic horn of twice the length, the three edges of which are
denticulate and fenestrated, each with a series of square pores. Length of
the two joints = 1 : 3, breadth = 2 : 4. Thorax thorny, with three broad
fenestrated divergent ribs, which are separated by three large ovate holes
(twice as long as the cephalis) and have their prominent distal ends
connected below by a broad circular ring of lattice-work (with irregular
polygonal small meshes). Peristome wide, two-thirds as broad as the thorax,
with a circular corona of small square pores and alternating prominent
small teeth.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.07 long, 0.09
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


6. _Clathrocanium reginæ_, n. sp. (Pl. 64, fig. 4).

  _Clathrocorona reginæ_, Haeckel, 1881, Prodromus, p. 431.

Cephalis hemispherical, with irregular roundish pores and a prismatic
club-shaped horn of twice the length, the three edges of which are
denticulate and fenestrated. Length of the two joints = 1 : 3, breadth =
1 : 4. Thorax thorny, with three broad triangular, fenestrated and
nodulated ribs, which are separated by three large ovate holes (twice as
long as the cephalis) and have their prominent distal ends connected below
by a circular ring of lattice-work. Peristome constricted, as broad as the
thorax, with a corona of short spines.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.08 long, 0.12
broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



Genus 541. _Lamprodiscus_,[158] Ehrenberg, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 831.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
divergent lateral ribs in the wall of the flat, conical, discoidal, or
pyramidal thorax. Cephalis with a horn. Peristome smooth, without corona of
spines.

{1213}The genus _Lamprodiscus_, and the following nearly allied
_Lampromitra_, differ from all preceding Sethopilida in the complete
connection of the three thoracic feet by lattice-work, so that they are
imbedded in the thorax-wall as prominent ribs and are not prolonged beyond
the margin as free feet. The shell is commonly very flat, conical or
pyramidal, sometimes nearly discoidal. The margin of _Lamprodiscus_ is
simple, smooth.


1. _Lamprodiscus monoceros_, Ehrenberg.

  _Lamprodiscus monoceros_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 295, Taf. vii. fig. 2.

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 5,
breadth = 1 : 8. Cephalis spherical, hyaline, without pores, with an
oblique conical horn of the same length. Thorax flat, campanulate, nearly
hemispherical, with convex lateral outlines, and regular hexagonal meshes,
increasing gradually in size towards the mouth. Bars very thin. Peristome
smooth.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.1 long, 0.16 broad.

_Habitat._--Western Tropical Pacific (Philippine Sea), Station 200,
surface.


2. _Lamprodiscus coscinodiscus_, Ehrenberg.

  _Lamprodiscus coscinodiscus_, Ehrenberg, 1872, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 295, Taf. vii. fig. 3.

Shell smooth, with sharp collar stricture. Thorax of the same form and
structure as in the preceding species, differing from it mainly in the
structure of the smooth circular margin, which is composed of a ring of
very small square pores. Length of the two joints = 1 : 4, breadth = 1 : 8.
Cephalis with small hexagonal pores, without horn or with a short
rudimentary horn. Lateral outlines of the campanulate thorax in the upper
part concave, in the lower convex.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.08 long, 0.16 broad.

_Habitat._--Tropical Pacific, Stations 206, 224, 266, &c., surface.


3. _Lamprodiscus tricostatus_, n. sp.

Shell smooth with deep collar stricture. Length of the two joints = 1 : 3,
breadth = 1 : 7. Cephalis  spherical, with an oblique conical horn of twice
the length and small circular pores. Thorax flatly conical, twice as broad
as high, with straight lateral outline, and regular hexagonal meshes,
increasing gradually in size towards the mouth; bars very thin. Peristome
or margin of the basal mouth circular, smooth.  Very similar to _Theopilium
tricostatum_ (Pl. 70, fig. 6), but without abdomen. Differs from the two
preceding species mainly in the conical form of the thorax and the less
delicate network.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.1 long, 0.2 broad.

_Habitat._--Cosmopolitan, Mediterranean, Atlantic, Indian, Pacific;
surface.


{1214}4. _Lamprodiscus lævis_, Haeckel.

  _Eucecryphalus lævis_, R. Hertwig, 1879, Organism. d. Radiol., p. 77,
  Taf. viii. figs. 6, 6_a_, 6_b._

Shell smooth, with distinct collar stricture. Length of the two joints =
1 : 3, breadth = 1 : 6. Cephalis subspherical, with small circular pores
and an oblique conical horn of twice the length. Thorax flat, pyramidal,
twice as broad as long, with three strong, straight divergent edges and
subregular roundish pores. Peristome smooth.

_Dimensions._--Cephalis 0.025 diameter; thorax 0.08 long, 0.16 broad.

_Habitat._--Mediterranean (Messina), R. Hertwig, surface.



Genus 542. _Lampromitra_, Haeckel,[159] 1881, Prodromus, p. 431.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
divergent lateral ribs in the wall of the flat conical or pyramidal thorax.
Cephalis commonly with a horn. Peristome with a corona of spines.

The genus _Lampromitra_ differs from the preceding and nearly allied
_Lamprodiscus_ only in the development of a dentated peristome, or an
elegant corona of teeth around the wide open mouth. It bears therefore to
the latter the same relation that _Clathrocorona_ does to _Clathrocanium_.


1. _Lampromitra coronata_, n. sp. (Pl. 60, fig. 7, 7_a_).

Shell flat, conical, with slight collar stricture. Length of the two joints
= 1 : 2, breadth = 2 : 7. Cephalis hemispherical, with a conical oblique
horn of twice the length, and small subregular hexagonal pores. Thorax with
larger, subregular, hexagonal meshes, six to eight times as broad as the
bars. Peristome or basal margin of the thorax circular, with a marginal
ring of smaller polygonal meshes and a triple coronal of short spines; two
external rings of short conical centrifugal spines, and an internal ring of
thin centripetal rods (fig. 7_a_). In fig. 7 the shell is seen from below
and exhibits very distinctly the internal cross of the collar septum,
composed of the four divergent cortinar bars; between the latter descend
the four pear-shaped lobes of the central capsule (each containing an oil
globule), whilst the apical part of the capsule (with the nucleus) is
hidden in the large cap-shaped cephalis.

_Dimensions._--Cephalis 0.03 long, 0.07 broad; thorax 0.06 long, 0.2 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Lampromitra quadricuspis_ (Pl. 58, fig. 7).

Shell flat, conical, with sharp collar stricture. Length of the two joints
= 1 : 3, breadth = 2 : 10. Cephalis hemispherical, with subregular circular
pores and an oblique, conical, occipital horn of twice {1215}the length,
bearing three divergent lateral branches, which are directed upwards, and
correspond to the three thoracic ribs. Further down, near the collar
stricture, a short divergent frontal horn arises. Thorax with irregular
roundish pores of different sizes, three to six times as broad as the bars.
Peristome with a simple coronal of short, conical, divergent spines, about
as long as the diameter of the cephalis.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.06 long, 0.2 broad.

_Habitat._--North Atlantic, Canary Islands, surface.


3. _Lampromitra furcata_, n. sp. (Pl. 58, fig. 8).

Shell flat, conical, with deep collar stricture, very similar in form and
structure to the preceding species; differs from it in the shape of the
peristome and the armature of the cephalis, which bears a conical, forked,
occipital horn of the same length, and a small rudimentary divergent
frontal horn. Length of the two joints = 1 : 2, breadth = 1 : 6. The four
pores of the collar septum (two larger cardinal and two smaller jugular)
exhibit in this species a peculiar asymmetry (fig. 8). The peristome bears
a simple coronal of spines as long as the diameter of the cephalis. The
major part of them is forked, some irregularly branched.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.18
broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.


4. _Lampromitra pyramidalis_, n. sp.

Shell flat, pyramidal, smooth, with slight collar stricture. Length of the
two joints = 1 : 4, breadth = 1 : 9. Cephalis subspherical, with an oblique
pyramidal horn of twice the length, and small circular pores. Thorax with
three strong, divergent, straight ribs and three flat triangular sides
between them, with subregular hexagonal pores, increasing in size towards
the mouth. Peristome with a simple coronal of large and numerous divergent,
conical spines, half as long as the shell.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.18
broad.

_Habitat._--South Atlantic, Station 325, depth 2650 fathoms.


5. _Lampromitra huxleyi_, Haeckel (Pl. 59, fig. 1).

  _Eucecryphalus huxleyi_, Haeckel, 1879, Natürl. Schöpfungsgesch., Edit.
  vii. Taf. xvi. fig. 9.

Shell flat, conical, spiny, with slight collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 8. Cephalis hemispherical, with a short
conical horn of the same length. Thorax with irregular polygonal pores.
Peristome with three coronals of divergent bristle-shaped spines; the first
directed obliquely upwards, the second outwards, and the third nearly
vertically, downwards; the bristles of the latter are much longer, about as
long as the height of the shell.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.16
broad.

_Habitat._--Australia (east coast), Station 169, surface.


{1216}6. _Lampromitra schultzei_, Haeckel.

  _Eucecryphalus schultzei_, Haeckel, 1862, Monogr. d. Radiol., p. 309,
  Taf. v. figs. 16-19.

Shell flat, conical, smooth, with slight collar stricture. Length of the
two joints = 1 : 3, breadth = 1 : 8. Cephalis hemispherical, with a small
conical horn of half the length, and very small roundish pores. Thorax with
three strong, straight ribs and irregular polygonal pores, which are much
larger in the middle part than in the upper or lower part. Peristome with a
double coronal of short, conical, divergent spines; the superior obliquely
ascending, the inferior vertically descending. (Named in honour of the late
Professor Max Schultze, the illustrious histologist.)

_Dimensions._--Cephalis 0.025 diameter; thorax 0.07 long, 0.2 broad.

_Habitat._--Mediterranean, Messina, surface.


7. _Lampromitra arborescens_, n. sp, (Pl. 60, fig. 8, 8_a_).

Shell flat, pyramidal, spiny, with sharp collar stricture. Length of the
two joints = 1 : 3, breadth = 2 : 10. Cephalis cap-shaped, with an oblique,
slender, conical horn of twice the length, and small circular pores. Thorax
with three slight almost obliterated ribs and three vaulted sides between
them, with irregular roundish pores. The three ribs are distinct in the
proximal, not in the distal part. Peristome with a double coronal of
smaller squarish pores and numerous divergent spines; the larger spines are
irregularly branched and as long as the diameter of the cephalis.

_Dimensions._--Cephalis 0.15 long, 0.03 broad; thorax 0.04 long, 0.2 broad.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.


8. _Lampromitra dendrocorona_, n. sp. (Pl. 58, fig. 9).

Shell flat, conical, with smooth surface and deep collar stricture. Length
of the two joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with a
slender occipital horn of three times the length, and a small divergent
frontal horn. Thorax with three strong prominent straight ribs and
irregular polygonal meshes, increasing in size towards the mouth. Peristome
with a dense coronal of numerous short conical spines and twenty-four to
thirty larger arborescent spines, longer than the diameter of the cephalis.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 543. _Callimitra_,[160] Haeckel, Prodromus, 1881, p. 431.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
vertical latticed wings, which stretch between the three divergent lateral
ribs of the thorax and the vertical horn of the cephalis. No frontal horn.

{1217}The genus _Callimitra_, and the two following nearly allied genera,
_Clathromitra_ and _Clathrocorys_, form together a peculiar small group,
the Callimitrida, living in the Central Pacific, and differing from the
other Sethopilida in some remarkable points, derived perhaps directly from
the Archiscenida, _Archiscenium_ and _Pteroscenium_, by the development of
thoracic network between the three cortinar feet. In the centre of the
collar septum, where these feet are united, there arises a vertical free
columella, prolonged over the top of the cephalis as a free horn, and this
horn is connected with the three thoracic ribs by three vertical
fenestrated wings.


1. _Callimitra carolotæ_, n. sp. (Pl. 63, figs. 1, 7, 8).

Cephalis campanulate, conical, with irregular, polygonal pores, and a thin
bristle-shaped apical horn of the same length. Length of the two joints =
3 : 6, breadth = 2 : 6. Thorax in the upper half with irregular network, in
the lower half with parallel transverse bars; in each of its three sides
descend two convergent pairs of stronger, parallel, curved ribs, not
confluent at the peristome. Each of the three vertical wings with eight
stronger ribs, three arising from the cephalis, five from each foot.
Dedicated to my dear mother Charlotte Sethe.

_Dimensions._--Cephalis 0.07 long, 0.05 broad; thorax 0.15 long, 0.15
broad.

_Habitat._--Central Pacific, Station 270, depth 2925 fathoms.


2. _Callimitra annæ_, n. sp. (Pl. 63, fig. 2).

Cephalis campanulate, conical, with irregular, polygonal pores, and a thin
bristle-shaped horn of the same length. Length of the two joints = 1 : 2,
breadth = 1 : 3. Thorax nearly in its whole extent with parallel transverse
bars, which are crossed by two convergent systems of parallel beams; in
each of its three sides descend four convergent pairs of stronger,
parallel, curved ribs, not confluent at the peristome. Each of the three
vertical wings with six stronger ribs, three arising from the cephalis,
three from each foot. Dedicated to my dear first wife Anna Sethe.

_Dimensions._--Cephalis 0.05 long, 0.05 broad; thorax 0.12 long, 0.18
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


3. _Callimitra agnesæ_, n. sp. (Pl. 63, fig. 5).

Cephalis pear-shaped, with irregular, square pores, and a slender
bristle-shaped horn twice as long. Length of the two joints = 1 : 3,
breadth = 1 : 5. Thorax in its whole extent with parallel transverse bars,
which are crossed by two converging and crossed systems of parallel beams;
in each of its three sides descend five convergent pairs of stronger,
parallel, curved ribs, the two or three upper of which are crossed at the
peristome. Each of the three vertical wings with five stronger ribs, three
arising from the cephalis and the horn, two from each foot.  Dedicated to
my dear second wife Agnes Huschke.

_Dimensions._--Cephalis 0.05 long, 0.05 broad; thorax 0.15 long, 0.22
broad.

_Habitat._--Central Pacific, Station 273, depth 2350 fathoms.


{1218}4. _Callimitra elisabethæ_, n. sp. (Pl. 63, fig. 6).

Cephalis nearly hemispherical, with irregular square pores, and a strong
prismatic horn thrice the length. Length of the two joints = 2 : 7, breadth
= 2 : 9. Thorax in the upper third with irregular network, in the lower
two-thirds with parallel transverse bars which are crossed by two
convergent systems of parallel beams; in each of its three sides descend
three convergent pairs of stronger, parallel, curved ribs; the two ribs of
the uppermost pair are united and confluent in a single odd rib in the
lower half of the thorax. Each of the three vertical wings with seven
stronger ribs, three arising from the cephalis and the horn, four from each
foot. Dedicated to my dear elder daughter Elizabeth Haeckel.

_Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.15 long, 0.2 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


5. _Callimitra emmæ_, n. sp. (Pl. 63, figs. 3, 4).

Cephalis campanulate, with irregular, polygonal pores, and very thin bars
(of the same shape as in the thorax) and with a thin bristle-shaped horn
twice the length. Length of the three joints = 3 : 6, breadth = 2 : 9.
Thorax in its whole extent with an arachnoidal network similar to that in
the cephalis and the three wings, composed of very numerous parallel
threads, which are crossed by two crossed diagonal systems of parallel
threads. In each of the three sides of the thorax descend five convergent
pairs of stronger ribs, the three upper of which are crossed and form large
rhomboidal meshes. Each of the three vertical wings with ten stronger ribs,
four arising from the cephalis and each horn, six from each foot. Dedicated
to my dear younger daughter Emma Haeckel.

_Dimensions._--Cephalis 0.07 long, 0.06 broad; thorax 0.15 long, 0.22
broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



Genus 544. _Clathromitra_,[161] Haeckel, 1881, Prodromus, p. 432.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
vertical latticed wings, which stretch between the three divergent lateral
ribs of the thorax and the vertical horn of the cephalis. The front of the
latter is armed with a large frontal horn.

The genus _Clathromitra_ differs from the preceding similar _Callimitra_ in
the development of a free frontal or sternal horn, a prolongation of an
internal obliquely ascending rod, opposite to the caudal foot. Therefore
the shell in this genus possesses five divergent free spines, two cephalic
horns, and three thoracic feet. The lattice-work of the three vertical
wings is not so delicate as in _Callimitra_.


{1219}1. _Clathromitra pterophormis_, n. sp. (Pl. 57, fig. 8).

Cephalis very large, hemispherical, about as long and half as broad as the
three-sided pyramidal thorax; both with irregular, polygonal meshes. Apical
horn three to four times as long as the frontal horn and the three basal
feet. All five spines three-sided prismatic, with nearly smooth edges.
Three lateral wings half as broad as the cephalis.

_Dimensions._--Cephalis 0.05 long, 0.1 broad; thorax 0.05 long, 0.15 broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


2. _Clathromitra pentacantha_, n. sp.

Cephalis large, hemispherical, half as long as the three-sided pyramidal
thorax; both with irregular, roundish meshes. Apical horn of about the same
length as the frontal horn, and twice as long as the three basal feet. All
five spines three-sided prismatic, with denticulated edges. Three lateral
wings about as broad as the cephalis.

_Dimensions._--Cephalis 0.04 long, 0.08 broad; thorax 0.1 long, 0.2 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.



Genus 545. _Clathrocorys_,[162] Haeckel, 1881, Prodromus, p. 432.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
prominent lateral ribs on the thorax, alternating with three large holes
(or thoracic gates). The three ribs are connected with the central apical
horn of the cephalis by three vertical latticed wings.

The genus _Clathrocorys_ differs from the two preceding nearly allied
genera in the incomplete fenestration of the thorax, the three perradial
ribs of which are separated by three large interradial holes. It has
therefore the same relation to _Callimitra_ that _Clathrocanium_ bears to
_Dictyophimus_.


1. _Clathrocorys murrayi_, n. sp. (Pl. 64, fig. 8).

Cephalis pear-shaped, with irregularly square pores. From the centre of its
base there arise four strong, prismatic, radial beams of nearly equal size,
the vertical, straight, cephalic horn being little longer than the three
divergent, somewhat curved feet. In the three meridional planes (between
the horn and each foot) a few rather thick branches arise, which by
communication of the ramules form the three vertical latticed wings; each
wing with two large meshes, three to five meshes of medium size, and three
to four parallel arachnoidal rows of small, square, distal meshes. The
three walls of the flat pyramidal thorax (between every two feet) are
formed in the upper part by squarish network {1220}similar to that of the
cephalis, in the middle part by a single row of arches separated by thin
threads, and in the lower part by a narrow band of arachnoidal network.
Dedicated to Dr. John Murray.

_Dimensions._--Cephalis 0.05 long, 0.05 broad; thorax 0.04 long, 0.15
broad; apical distance of every two feet 0.15, of each foot and the horn
0.17.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Clathrocorys teuscheri_, n. sp. (Pl. 64, fig. 10).

Cephalis pear-shaped, with irregular, square pores. From the centre of its
base there arise seven prismatic, radial beams of equal strength,
supporting the lattice-work of the wall; the single vertical beam is
prolonged into the apical horn; six others lie in the three meridian planes
(between the horn and each foot); three ascending end in the wall of the
cephalis, three descending are prolonged into the three strong feet, which
are longer than the horn. In each meridional plane there arise four thicker
and several thinner bars, which by communication of their ramules form the
three latticed wings; each wing with a single very large mesh, two meshes
of medium size, and a narrow marginal band of small, square pores. The
three walls of the flat pyramidal thorax are formed in the upper part by
squarish network similar to that of the cephalis, in the lower part by a
narrow band of the same; between them a large hole. Dedicated to Dr.
Reinhold Teuscher.

_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.15
broad; apical distance of every two feet 0.2, of each foot and the horn
0.2.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


3. _Clathrocorys giltschii_, n. sp. (Pl. 64, fig. 9).

Cephalis pear-shaped, with irregular, polygonal pores. From the centre of
its base there arise seven prismatic, radial beams of different strength;
the single vertical beam bears six lateral branches (parallel to the three
ascending supporting beams), and is prolonged into the apical horn; six
others lie in the three meridional planes (between the horn and each foot);
three weaker ascending beams end in the wall of the cephalis, three
stronger descending are prolonged into the three large diverging feet,
which are twice as long as the cephalic horn. The network of the three
wings and of the three-sided pyramidal thorax is about the same as in the
preceding species, but much more developed; the marginal bands with the
squarish network are much broader, and an arachnoidal wicker-work of very
thin thread-like bars fills out the large meshes. Dedicated to Mr. Adolf
Giltsch.

_Dimensions._--Cephalis 0.04 long, 0.04 broad; thorax 0.12 long, 0.2 broad;
apical distance of every two feet 0.24, of each foot and the horn 0.2.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.



Genus 546. _Eucecryphalus_,[163] Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 836.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
free collar {1221}wings or solid spines arising from the collar stricture,
and freely prominent between the horned cephalis and the flat conical
thorax.

The genus _Eucecryphalus_, according to the restricted definition here
given, comprises only those Sethopilida in which the three primary cortinar
beams are perfectly free divergent collar wings, _i.e._, free spines
arising outside the shell from the collar stricture, between the cephalis
and thorax. The type of this genus (which I formerly united with other
Sethopilida) remains _Eucecryphalus gegenbauri_.



Subgenus 1. _Eucyrtomphalus_, Haeckel, 1881, Prodromus, p. 431.

_Definition._--Peristome or margin of the basal mouth of the thorax smooth,
without marginal spines.


1. _Eucecryphalus corocalyptra_, n. sp.

Shell flatly conical, with slight collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 6. Cephalis subspherical, with an oblique
conical horn twice its length. Thorax conical, twice as broad as long, with
regular hexagonal meshes and straight lateral outlines. From the collar
stricture there arise three slender conical spines, about as long as the
thorax, divergent downwards. Similar to _Corocalyptra agnesæ_ (Pl. 59, fig.
3), but without lumbar stricture and abdomen. Peristome or basal margin of
the mouth of the thorax smooth, simple.

_Dimensions._--Cephalis 0.3 diameter; thorax 0.09 long, 0.18 broad.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface.


2. _Eucecryphalus halicalyptra_, n. sp.

Shell flat, campanulate, with distinct collar stricture. Length of the two
joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with two
divergent conical horns, a major occipital and a minor frontal horn. Thorax
with subregular hexagonal meshes and concave-convex lateral outlines,
campanulate. From the collar stricture there arise three divergent
bristle-shaped spines, nearly horizontal, about half as long as the thorax.
Peristome smooth, with a marginal coronal of small square pores.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

_Habitat._--Central Pacific, Stations 266 to 274, surface.



Subgenus 2. _Eucecryphalium_, Haeckel.

_Definition._--Peristome or margin of the basal mouth of the thorax
dentate, with a coronal of marginal spines.


{1222}3. _Eucecryphalus cuvieri_, n. sp.

Shell flatly conical, with slight collar stricture. Length of the two
joints = 1 : 8, breadth = 2 : 10. Cephalis hemispherical, with an oblique
pyramidal horn twice as long. Thorax with straight outlines and regular
hexagonal meshes, increasing in size towards the mouth. From the collar
stricture there arise three stout conical spines, half as long as the
thorax, and diverging downwards. Peristome with a ring of small square
pores and alternate conical divergent spines. Differs from the similar
_Clathrocyclas alcmenæ_ (Pl. 59, fig. 6), mainly in the simple apical horn
and the possession of the three collar fundamental spines.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.15 long, 0.2 broad.

_Habitat._--Tropical Atlantic, Station 342, depth 1445 fathoms.


4. _Eucecryphalus mülleri_, n. sp.

Shell flatly campanulate, of nearly the same structure as and similar form
to that of the preceding species. Differs from it mainly in the
considerable size of the cephalic horn and the three collar spines, which
are bristle-shaped and longer than the shell. Length of the two joints =
1 : 4, breadth = 2 : 8. The peristome bears a double marginal ring of
divergent conical spines, the upper being directed upwards, the lower
downwards.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.16
broad.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


5. _Eucecryphalus gegenbauri_, Haeckel.

  _Eucecryphalus gegenbauri_, Haeckel, 1862, Monogr. d. Radiol., p. 308,
  Taf. v. figs. 12-15.

  _Eucecryphalus gegenbauri_, R. Hertwig, 1879, Organism. d. Radiol., p.
  76, Taf. viii. figs. 5, 5_a_, 5_b_.

Shell flatly conical, campanulate, with slight collar stricture. Length of
the two joints = 1 : 4, breadth = 1 : 8. Cephalis hemispherical, with a
conical horn of the same length, and very small pores. Thorax about twice
as broad as high, with large, subregular, hexagonal meshes, increasing in
size downwards. In the upper half of the thorax the meshes are filled up by
an extremely delicate arachnoidal network. From the collar stricture there
arise three divergent bristle-shaped spines half as long as the thorax.
Peristome with a double coronal of small square pores (the inner smaller
and more numerous than the outer), and with a single coronal of divergent
marginal spines. This cosmopolitan species is rather variable.

_Dimensions._--Cephalis 0.02 to 0.03 diameter; thorax 0.1 to 0.12 long,
0.02 to 0.25 broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific,
surface.


{1223}6. _Eucecryphalus campanella_, Haeckel.

  _Pterocodon campanella_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 82, Taf. xix. fig. 2.

Shell campanulate, conical, with sharp collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 2. Cephalis hemispherical, with a short
conical horn half as long, and very small pores. Thorax campanulate, as
broad as high, with large roundish meshes, increasing in size downwards.
From the collar stricture arise three strong, divergent, somewhat curved
spines, nearly as long as the thorax. Peristome with a coronal of ten to
twelve strong, conical, marginal spines, which are nearly parallel,
directed downwards, a little curved, and half as long as the thorax. In the
complete specimen examined by me, the apical horn, the three lateral wings
and twelve terminal feet were well preserved.

_Dimensions._--Cephalis 0.02 to 0.03 diameter; thorax 0.06 to 0.07 long and
broad.

_Habitat._--Fossil in Barbados.



Genus 547. _Amphiplecta_,[164] Haeckel, 1881, Prodromus, p. 424.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta) with three
internal thoracic ribs, enveloped by the network of the thorax. Cephalis
with a large apical opening, surrounded by a coronal of spines.

The genus _Amphiplecta_ (or _Amphicryphalus_) comprises some very peculiar
forms of Sethopilida, probably widely remote from the other genera of this
subfamily, and derived directly from the Plectanida (compare above, p.
921). The cortinar tripodium, composed of three feet divergent downwards,
and one apical horn ascending upwards (in some species also a second
frontal horn) is here enclosed in the cavity of a two-jointed shell, which
exhibits two large openings, a smaller apical hole in the top of the
cephalis, and a larger terminal mouth on the thorax. There is no trace of a
sagittal ring.


1. _Amphiplecta amphistoma_, n. sp.

Cephalis subspherical, spiny, with sharp collar stricture on the base; its
apical opening central, surrounded by a coronal of twelve to eighteen short
spines. Length of the two joints = 7 : 8, breadth = 6 : 20.  Thorax flatly
conical, armed with bristle-shaped spines.  Meshes of the network in both
joints subregular, hexagonal, six to eight times as broad as the bars.
Basal mouth bristly.

_Dimensions._--Cephalis 0.07 long, 0.06 broad; thorax 0.08 long, 0.2 broad.

_Habitat._--Central Pacific, Station 274, surface.


2. _Amphiplecta acrostoma_, n. sp. (Pl. 97, fig. 10).

Cephalis subspherical, spiny, with distinct collar stricture on the base,
its apical opening central, surrounded by a coronal of six to nine
divergent denticulate spines. Length of the two joints = 5 : 6,
{1224}breadth = 4 : 15. Thorax flatly conical, armed with denticulate
spines. Meshes of both joints irregular, polygonal, twice to six times as
broad as the bars. Basal mouth armed with longer, divergent, denticulate
spines.

_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.15
broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


3. _Amphiplecta callistoma_, n. sp. (Pl. 59, fig. 2).

Cephalis flat, cap-shaped, spiny, with obliterated collar stricture on the
base; its apical opening excentric, oblique, surrounded by a coronal of ten
to twenty bristle-shaped spines. Length of the two joints = 4 : 5, breadth
= 7 : 25. Thorax flatly conical, armed with long bristle-shaped spines.
Meshes of both joints irregular, hexagonal, twice to six times as broad as
the bars. Basal mouth with a double irregular coronal of small square
pores, and of bristle-shaped divergent spines.

_Dimensions._--Cephalis 0.04 long, 0.07 broad; thorax 0.05 long, 0.25
broad.

_Habitat._--Central Pacific, Station 271, surface.



Genus 548. _Lychnocanium_,[165] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta), with three
solid terminal feet on the peristome. No thoracic ribs. Cephalis with a
horn.

The genus _Lychnocanium_, very rich in common living and fossil forms,
comprises those Sethopilida in which the thorax bears three simple terminal
feet around the mouth, but no lateral ribs in its wall. It has therefore
been probably derived from _Dictyophimus_ by reduction and loss of these
three lateral ribs. The mouth is commonly more or less constricted. The
three feet surrounding it are sometimes divergent, straight or curved, at
other times parallel and vertical, straight, or curved and convergent. The
central capsule exhibited in some living species three or four distinct
lobes, filling up the upper half of the thorax.



Subgenus 1. _Lychnocanella_, Haeckel.

_Definition._--Feet divergent, straight or scarcely curved; their terminal
distance greater than their basal distance.


1. _Lychnocanium lanterna_, n. sp. (Pl. 61, fig. 7).

Shell conical, rough, with slight collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 3. Cephalis with a stout pyramidal horn of
the same length. Thorax pear-shaped, twice as {1225}broad as the
constricted mouth, with regular, circular pores of the same breadth as the
bars. Three feet pyramidal, little divergent, straight, about as long as
the cephalis.

_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.09 long, 0.08
broad.

_Habitat._--Central Pacific, Stations 263 to 268, depth 2650 to 2900
fathoms.


2. _Lychnocanium continuum_, Ehrenberg.

  _Lychnocanium continuum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. vii. fig. 11.

Shell smooth, with distinct collar stricture. Length of the two joints =
1 : 3, breadth = 1 : 3. Cephalis subspherical with a conical horn of the
same length. Thorax pear-shaped, twice as broad as the constricted mouth,
nearly hyaline, with a very small number of scattered minute pores. Three
feet pyramidal, little divergent, straight, about as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


3. _Lychnocanium pyriforme_, n. sp. (Pl. 61, fig. 11).

Shell pear-shaped, rough, with sharp collar stricture. Length of the two
joints = 1 : 4, breadth = 1 : 5. Cephalis hemispherical, with a conical
horn of the same length. Thorax inflated, four times as broad as the
constricted tubular mouth, with regular, circular pores. Three feet
pyramidal, straight, divergent, about as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.12 long, 0.15
broad.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, many Stations; also
fossil in Barbados.


4. _Lychnocanium favosum_, n. sp. (Pl. 61, fig. 6).

Shell campanulate, rough, with slight collar stricture. Length of the two
joints = 1 : 5, breadth = 1 : 6. Cephalis hemispherical, with a rudimentary
pyramidal horn of half the length. Thorax subglobular, three times as broad
as the constricted mouth, with regular, circular pores, and an elevated
hexagonal framework between them. Three feet cylindrical, slender,
straight, divergent, twice to three times as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.025 broad; thorax 0.1 long, 0.12
broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


5. _Lychnocanium nodosum_, n. sp. (Pl. 61, fig. 14).

Shell campanulate, nodose, with deep collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a rudimentary
conical horn of half the length. Thorax nearly hemispherical, twice as
broad as the flat mouth, with regular, circular pores, and a variable
{1226}number of scattered, conical, fenestrated protuberances. Three feet
very large, prismatic, straight, divergent, twice as long as the thorax.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.12
broad.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.


6. _Lychnocanium carinatum_, Ehrenberg.

  _Lychnocanium carinatum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. viii. fig. 5.

Shell campanulate, with deep collar stricture. Length of the two joints =
1 : 3, breadth = 1 : 3. Cephalis subglobular, with a slender horn of the
same length. Thorax conical, twice as broad as the flat mouth, with fifteen
to twenty prominent, longitudinal, divergent ribs, alternating with the
same number of rows of pores. Three feet slender, prismatic, straight,
divergent, twice as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


7. _Lychnocanium ventricosum_, Ehrenberg.

  _Lychnocanium ventricosum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 80, Taf. vii. fig. 12.

Shell pear-shaped, rough, with deep collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a stout conical
horn twice the length. Thorax conical, three times as broad as the
constricted mouth, with irregular, roundish pores of different sizes. Three
feet stout, conical, divergent, half as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.09
broad.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms; fossil in Barbados.


8. _Lychnocanium tribulus_, Ehrenberg.

  _Lychnocanium tribulus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. vii. fig. 1.

Shell pear-shaped, nodose, with distinct collar stricture. Length of the
two joints = 1 : 4, breadth = 1 : 4. Cephalis subglobular, with a conical
horn twice the length. Thorax ovate, twice as broad as the constricted
mouth, with irregular, roundish pores of different sizes. Three stout feet
strongly divergent, pyramidal, about as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; 0.08 long, 0.08 broad.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Lychnocanissa_, Haeckel.

_Definition._--Feet divergent, more or less curved; their terminal distance
greater than their basal distance.


{1227}9. _Lychnocanium fortipes_, n. sp. (Pl. 61, fig. 12).

Shell inflated, rough, with distinct collar stricture. Length of the two
joints = 1 : 5, breadth = 1 : 6. Cephalis small, hemispherical, with a
pyramidal horn of half the length. Thorax subglobular, truncate, twice as
broad as the constricted mouth, with large, regular, circular pores and
very thin bars. Three feet very stout, prismatic, twice as long as the
thorax, widely divergent, curved with convexity outwards, club-shaped at
the distal end, with denticulate edges.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.1 long, 0.12 broad.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.


10. _Lychnocanium falciferum_, Ehrenberg.

  _Lychnocanium falciferum_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig.
  7; Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 4.

  _Lithomelissa falcifera_, Haeckel, 1862, Monogr. d. Radiol., p. 303.

Shell inflated, rough, with deep collar stricture. Length of the two joints
= 1 : 3, breadth = 1 : 3. Cephalis small, with a conical horn of half the
length. Thorax subglobular, truncate, three times as broad as the
constricted mouth, with small, regular, circular pores. Three feet widely
divergent, twice as long as the thorax, curved like a crescent, with strong
convexity outwards.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


11. _Lychnocanium tuberosum_, n. sp. (Pl. 61, fig. 13).

Shell conical, tuberculate, with deep collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a conical horn
of the same length. Thorax inflated, twice as broad as the flat mouth, with
small, irregular, roundish pores and scattered fenestrated tubercles. Three
feet very large, angular, three times as long as the thorax, curved like a
crescent, with strong convexity outwards.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.12
broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


12. _Lychnocanium hirundo_, Ehrenberg.

  _Lychnocanium hirundo_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. vii. fig. 8.

  _Lithornithium hirundo_, Ehrenberg, 1854, Mikrogeol., Taf. xix. fig. 53.

  _Lithocampe hirundo_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.
  Wiss. Berlin, p. 65.

Shell conical, tuberculate, with slight collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 4. Cephalis hemispherical, with a conical
horn of half the length. Thorax {1228}campanulate, twice as broad as the
flat mouth, with longitudinal, divergent ribs, alternating with rows of
small circular pores. Three feet divergent, striated, gradually lessening
from a broad base, twice as long as the thorax, curved like a crescent,
with convexity outwards.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08
broad.

_Habitat._--Fossil in Tertiary rocks of Barbados and the Mediterranean
(Sicily, Greece).


13. _Lychnocanium fenestratum_, n. sp. (Pl. 61, fig. 10).

Shell pear-shaped, rough, with slight collar stricture. Length of the two
joints = 1 : 4, breadth = 1 : 3. Cephalis subglobular, with a very large
prismatic horn, which is about as long as the shell, with three
denticulate, prominent, wing-like crests, which are pierced by a series of
pores. Thorax ovate, three times as broad as the constricted, prominent
mouth, with subregular, circular pores. Three feet arising somewhat above
the mouth, prismatic, with denticulate edges, about as long as the thorax,
divergent, curved, with convexity outwards.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.08
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


14. _Lychnocanium sigmopodium_, n. sp. (Pl. 61, fig. 15).

  ? _Lychnocanium tetrapodium_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 80, Taf. vii. fig. 3.

Shell campanulate, rough with distinct collar stricture. Length of the two
joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, with a slender
pyramidal horn twice the length. Thorax inflated, conical, with regular
circular pores and a wide open mouth of nearly the same breadth. Three feet
widely divergent, twice as long as the thorax, angular, S-shaped, or curved
with convexity inwards. (_Lychnocanium tetrapodium_ of Ehrenberg is perhaps
a variety of this species?).

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.09
broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, many stations
at various depths; also fossil in Barbados and Sicily.


15. _Lychnocanium trichopus_, Ehrenberg.

  _Lychnocanium trichopus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. vii. fig. 5.

Shell conical, smooth, with deep collar stricture. Length of the two joints
= 1 : 3, breadth = 1 : 3. Cephalis subspherical, with a rudimentary conical
horn of half the length. Thorax campanulate, with regular, circular pores
and wide open mouth of nearly the same breadth. Three feet divergent, very
slender, four to five times as long as the thorax, not broader than one
pore, S-shaped, or curved with convexity inwards in the distal half.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.09
broad.

_Habitat._--Fossil in Barbados.



{1229}Subgenus 3. _Lychnocanoma_, Haeckel.

_Definition._--Feet parallel, vertical, straight, or little curved;
divergent in the basal half, often convergent in the distal half; their
terminal distance about equal to the basal distance.


16. _Lychnocanium tripodium_, Ehrenberg.

  _Lychnocanium tripodium_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. vii. fig. 2.

Shell ovate, smooth, with distinct collar stricture. Length of the two
joints = 1 : 4, breadth = 1 : 4. Cephalis subglobular, with a slender
conical horn twice the length. Thorax inflated, twice as broad as the
constricted mouth, with small, regular, circular pores. Three feet slender,
prismatic, twice to three times as long as the thorax, nearly straight and
parallel, vertical.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.07 long, 0.07
broad.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms; also fossil in Barbados.


17. _Lychnocanium cypselus_, Ehrenberg.

  _Lychnocanium cypselus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. vii. fig. 10.

Shell slender, ovate, with slight collar stricture. Length of the two
joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, with a conical horn
of the same length. Thorax ovate, truncate, three times as broad as the
narrow, constricted mouth, with small, regular, circular pores. Three feet
slender, somewhat shorter than the thorax, little curved, with convexity
outwards, nearly parallel, vertical. (In the specimen figured by Ehrenberg,
the third foot was broken off.)

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


18. _Lychnocanium ovatum_, n. sp.

Shell ovate, rough, without external collar stricture. Length of the two
joints = 1 : 6, breadth = 1 : 5. Cephalis conical, with a stout conical
horn of the same length. Thorax ovate, four times as broad as the narrow
constricted mouth, with small, regular, circular pores, separated by
hexagonal frames of twice the breadth. Three feet cylindrical, half as long
as the thorax, and three times as long as broad, straight, parallel,
vertical.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax, 0.12 long, 0.1
broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


{1230}19. _Lychnocanium crassipes_, Ehrenberg.

  _Lychnocanium crassipes_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. vii. fig. 7.

Shell campanulate, rough, with deep collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a thin conical
horn of the same length. Thorax semi-ovate, three times as broad as the
narrow constricted mouth, with fifteen to twenty divergent, denticulate
ribs, alternating with the same number of rows of small, regular, circular
pores. Three feet very stout, as long as the thorax, cylindrical, nearly
straight and parallel, vertical, at the distal end clavate, spinulate or a
little forked.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.08
broad.

_Habitat._--Fossil in Barbados.


20. _Lychnocanium clavigerum_, n. sp. (Pl. 61, fig. 4).

Shell campanulate, sulcate, with sharp collar stricture. Length of the two
joints = 1 : 4, breadth = 1 : 5. Cephalis subglobular, with a
spindle-shaped papillate horn twice the length. Thorax nearly spherical,
truncate at both poles, three times as broad as the narrow, constricted,
somewhat tubular mouth, with fifteen to twenty elevated meridional ribs,
alternating with the same number of rows of circular pores. Three feet
slender, cylindrical, twice as long as the thorax, in the basal half
divergent, in the distal half convergent, club-shaped, with a thickened
papillate end.

_Dimensions._--Cephalis 0.02 long, 0.025 broad; thorax 0.08 long, 0.01
broad.

_Habitat._--Indian Ocean, Madagascar, surface (Rabbe).


21. _Lychnocanium pudicum_, n. sp. (Pl. 61, fig. 2).

Shell campanulate, with deep collar stricture. Length of the two joints =
1 : 3, breadth = 1 : 3. Cephalis hemispherical, hyaline (without pores),
with a short and thick club-shaped, spinulate horn of the same length.
Thorax subglobular, truncate at both poles, twice as broad as the
constricted mouth, with small, irregular, roundish pores. Three feet
somewhat shorter than the thorax, curved like a crescent, with convexity
outwards; their distal ends club-shaped, spinulate, convergent towards the
central axis.

_Dimensions._--Cephalis 0.02 long, 0.025 broad; thorax 0.06 long, 0.07
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 549. _Lychnodictyum_,[166] Haeckel, 1881, Prodromus, p. 432.

_Definition._--#Sethopilida# (vel Dicyrtida triradiata aperta), with three
latticed terminal feet on the peristome, without thoracic ribs. Cephalis
originally with a horn (sometimes lost).

{1231}The genus _Lychnodictyum_ differs from the preceding _Lychnocanium_
only in the fenestration of the three terminal feet, and bears therefore to
it the same relation that the ancestral _Tripocyrtis_ does to
_Dictyophimus_.


1. _Lychnodictyum challengeri_, Haeckel.

  _Dictyopodium challengeri_, Wyville Thomson, 1877, Atlantic, vol. i. p.
  234, fig. 52.

  _Dictyophimus_ (vel _Tripocyrtis_) _challengeri_, Haeckel, 1878,
  Protistenreich, p. 47, fig. 35.

Shell campanulate, smooth, with sharp collar stricture. Length of the two
joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a large,
oblique, pyramidal horn thrice the length. Thorax with three inflated
bosoms between the three decurrent ribs, which are prolonged into three
vertical, parallel, pyramidal, in the upper half fenestrated feet, as long
as the thorax. Pores regular, circular. Mouth constricted, flat, half as
broad as the thorax.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.08 long, 0.12 broad.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.


2. _Lychnodictyum wyvillei_, n. sp.

Shell pyramidal, smooth, with obliterated collar stricture. Length of the
two joints = 1 : 3, breadth = 1 : 5. Cephalis subspherical, with a large,
straight, pyramidal horn of twice the length. Thorax nearly tetrahedral,
inflated, with three rounded, decurrent ribs, which are prolonged into
three widely divergent, angular, curved feet, about as long as the shell,
with pyramidal fenestrated base. Pores regular, circular. Mouth
constricted, flat, half as broad as the thorax.

_Dimensions._--Cephalis 0.025 diameter; thorax 0.08 long, 0.12 broad.

_Habitat._--Central Pacific, Stations 266 to 274, depth 2350 to 2925
fathoms.


3. _Lychnodictyum scaphopodium_, n. sp. (Pl. 56, fig. 4).

Cephalis hemispherical, large, without horn, with irregular, small,
roundish pores. Thorax a little larger, campanulate, with three broad,
shovel-shaped, fenestrated, vertical feet, and larger, irregular pores. In
the figured specimen the third (posterior) foot was broken off. In another
specimen the three feet were somewhat longer and not so broad.

_Dimensions._--Cephalis 0.03 long, 0.05 broad; thorax 0.05 long, 0.06
broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


4. _Lychnodictyum sethopodium_, n. sp.

Cephalis hemispherical, large, with a rudimentary conical horn, and very
scarce small pores. Thorax twice as broad and long as the cephalis,
campanulate, with irregular, roundish pores, and three slender, pyramidal,
divergent feet twice the length, which in the upper half are fenestrated,
in the lower half solid.

_Dimensions._--Cephalis 0.025 long, 0.045 broad; thorax 0.05 long, 0.09
broad.

_Habitat._--South Atlantic, Station 330, surface.



{1232}Subfamily 2. SETHOPERIDA, Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Tripocyrtida# with the basal mouth of the shell fenestrated
(vel Dicyrtida triradiata clausa).



Genus 550. _Sethopera_,[167] Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa), with three
divergent ribs enclosed in the latticed wall of the thorax. Cephalis with a
horn.

The genus _Sethopera_ is probably the oldest form of the Sethoperida, and
may therefore be regarded as the common ancestral form of this subfamily.
The thorax exhibits three radial ribs, which are completely enclosed in its
wall. Sethopera may be derived either from _Dictyophimus_ or from another
of the Sethopilida (_Lamprodiscus, Clathrocanium_) by development of a
basal lattice-plate closing the mouth. There are often wide holes or open
spaces between the three radial ribs.


1. _Sethopera tricostata_, n. sp. (Pl. 97, fig. 11).

Cephalis subspherical, spinulate, with a pyramidal horn of the same length.
Length of the two joints = 5 : 8, breadth = 5 : 8. Thorax also nearly
spherical; in the upper half with three stout, prismatic, convex, divergent
ribs, and three large ovate holes between them; in the lower half with
numerous small and irregular pores, spinulate.

_Dimensions._--Cephalis 0.05 diameter; thorax 0.08 diameter.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Sethopera oceania_, Haeckel.

  _Lithopera oceania_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 297, Taf. iv. fig. 21.

Cephalis hemispherical, with a small bristle-shaped horn of half the length
(broken off in Ehrenberg's figure). Length of the two joints = 3 : 4,
breadth = 3 : 4. Thorax nearly spherical; in the upper half with three
divergent ribs, separated by some larger, irregular pores; in the lower
half with numerous small, irregular, roundish pores.

_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.04 long, 0.04
broad.

_Habitat._--North Atlantic, Station 354, surface; Canary Islands and
Azores.


3. _Sethopera pyrum_, Haeckel.

  ? _Lithopera pyrum_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 297.

Cephalis hemispherical, with a small conical horn of half the length.
Length of the two joints = 3 : 10, breadth = 3 : 7. Thorax pear-shaped,
with rather large, regular, quincuncial pores; {1233}its upper half with
three divergent ribs in the wall, half as broad as the subspherical lower
half. (The three ribs probably were overlooked by Ehrenberg.)

_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.07 broad.

_Habitat._--North Pacific, Station 256, surface; Californian Sea, 2600
fathoms, Ehrenberg.


4. _Sethopera lagena_, Haeckel.

  _Lithopera lagena_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. iii. fig. 4.

Cephalis pear-shaped, with a small conical horn of half the length. Length
of the two joints = 3 : 8, breadth = 3 : 6. Thorax smooth, pear-shaped,
with irregular roundish pores; in the wall of its upper third three
divergent thin ribs (sometimes wanting); the lower half inflated. (Compare
_Sethocapsa lagena_.)

_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.08 long, 0.06
broad.

_Habitat._--Fossil in Barbados.



Genus 551. _Lithopera_,[168] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.

_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa), with three
divergent ribs enclosed in the cavity of the thorax. Cephalis with a horn.

The genus _Lithopera_ is, like the preceding _Sethopera_, one of the most
simple and oldest forms of the Sethoperida, and exhibits three divergent
thoracic ribs, which are prolonged neither into lateral wings nor into
basal feet. But whilst in _Sethopera_ the three ribs are enclosed in the
lattice-work of the shell-wall, in _Lithopera_ they lie freely in its
cavity, and are overgrown by the enveloping shell-wall, being inserted on
its inner face with their distal ends. _Lithopera_ may be derived directly
from _Lithomelissa_, by development of lattice-work closing the
shell-mouth. Therefore the lower part of the cephalis is hidden in the
uppermost part of the thorax; only its upper part is free.


1. _Lithopera bacca_, Ehrenberg.

  _Lithopera bacca_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin,
  p. 297, Taf. viii. fig. 1.

Cephalis spherical, with small, irregular pores and a bristle-shaped spine
of half the length; its lower half hidden in the thorax. Length of the two
joints = 1 : 6, breadth = 1 : 5. Thorax ellipsoidal, smooth, with regular,
hexagonal, small pores, and very thin, thread-like bars. From the deep
collar stricture there arise three internal, divergent bars, which are
inserted at the uppermost third of the thorax.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.12 long, 0.1 broad.

_Habitat._--Tropical Pacific, Stations 200, 224, 266, 271, &c., surface.


{1234}2. _Lithopera bursella_, Ehrenberg.

_Lithopera bursella_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 297, Taf. x. fig. 4.

Shell of about the same form and structure as in the nearly allied
preceding species, but smaller, of more slender form, with smaller pores
and thinner bars. Length of the two joints = 1 : 5, breadth = 1 : 3. In the
specimen observed by me the three internal, divergent bars of the
ellipsoidal thorax (not seen by Ehrenberg) were as distinct as in the
similar preceding and following species.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.1 long, 0.06 broad.

_Habitat._--Indian Ocean, Zanzibar (Pullen), Madagascar (Rabbe), surface.


3. _Lithopera ananassa_, n. sp. (Pl. 57, fig. 3).

Shell of about the same form and structure as in the two preceding species,
but larger and more robust, and differing in the spiny surface. Length of
the two joints = 1 : 5, breadth = 1 : 4. Here also the lower half of the
spherical cephalis is submerged in the ellipsoidal thorax, and from the
collar stricture arise three strong, internal, divergent beams. The bars of
the hexagonal pores are much thicker than in the two preceding species.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.16 long, 0.12 broad.

_Habitat._--Tropical Atlantic, Stations 347 to 352, surface.


4. _Lithopera globosa_, n. sp.

Cephalis spherical, very small, with two divergent conical horns of half
the length; its lower half hidden in the thorax. Length of the two joints =
1 : 5, breadth = 1 : 5. Thorax spherical, with regular, circular,
hexagonally-framed pores. From the collar stricture arise three radial
internal beams, horizontally diverging, and inserted at the inside of the
thorax.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.15 diameter.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


5. _Lithopera gutta_, Ehrenberg.

  _Lithopera gutta_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin,
  p. 297, Taf. viii. fig. 2.

Shell pear-shaped, with sharp collar stricture. Length of the two joints =
1 : 4, breadth = 1 : 3. Cephalis spherical, with a conical horn of the same
length; its lower half hidden in the uppermost part of the ovate thorax,
and connected with its wall by three internal, cortinar beams. Pores of the
thorax very irregular in form and size, partly lobed.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.08 long, 0.06 broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms;
Philippine Sea (depth 3300 fathoms), Ehrenberg.



{1235}Genus 552. _Micromelissa_,[169] Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa), with three
divergent, solid, lateral wings. Cephalis with a horn.

The genus _Micromelissa_ differs from the two preceding genera in the free
prominence of the three cortinar ribs, forming three solid lateral wings.
Beyond these the thorax walls are convergent, and the basal mouth closed by
a lattice-plate. Therefore _Micromelissa_ may have arisen from
_Lithomelissa_ simply by development of this basal mouth-plate.


1. _Micromelissa bombus_, n. sp. (Pl. 57, fig. 14).

Shell smooth, with sharp collar stricture. Length of the two joints =
1 : 4, breadth = 1 : 5. Cephalis spherical, with an oblique conical horn of
the same length. Thorax subspherical, in the upper half with three conical,
downwardly diverging wings, about as long as its radius. Pores very small
and scarce.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.1 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Micromelissa vespa_, n. sp.

Shell smooth, with deep collar stricture. Length of the two joints = 2 : 5,
breadth = 2 : 3. Cephalis spherical, with an oblique pyramidal horn twice
the length. Thorax inversely ovate, in the upper half with three pyramidal
wings, which are equal to its breadth, little curved and diverging
downwards. Pores very small and scarce.

_Dimensions._--Cephalis 0.04 diameter; thorax 0.1 long, 0.06 broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


3. _Micromelissa apis_, n. sp.

Shell rough, with deep collar stricture. Length of the two joints = 2 : 3,
breadth = 2 : 4. Cephalis subspherical, with a straight conical horn of
half the length, and subregular, circular, double-contoured pores, of the
same breadth as the bars. Thorax little larger, subspherical, with
irregular, roundish pores, twice to four times as broad as the bars. From
its lower half arise three short conical wings, curved downwards, and half
as long as the cephalis.

_Dimensions._--Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.08
broad.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


{1236}4. _Micromelissa microptera_, Haeckel.

  _Lithomelissa microptera_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig.
  2; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 78, Taf. iii. fig. 13.

  _Lithomelissa microptera_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. p. 539, Taf. xxxiii. fig. 26.

Shell smooth, with distinct collar stricture. Length of the two joints =
4 : 6, breadth = 3 : 5. Cephalis ovate, with a straight sword-shaped horn
of the same length and very small pores, some larger ones above the
stricture. Thorax little larger, ovate, nearly hyaline, with very few and
small scattered pores. From its uppermost part arise three short conical
wings, scarcely half as long as the cephalic horn, little curved and
divergent downwards.

_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax 0.06 long, 0.05
broad.

_Habitat._--Fossil in Barbados.


5. _Micromelissa ventricosa_, Haeckel.

  _Lithomelissa ventricosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. iii. fig. 11.

Shell rough, with slight collar stricture. Length of the two joints =
1 : 7, breadth = 1 : 5. Cephalis small, hemispherical, with a small conical
horn of half the length. Thorax ovate, very large, papillate, with
irregular, roundish pores. From its basal part arise three short and stout
conical wings at great distances, shorter than the cephalis. (A
transition-form to _Sethocapsa_.)

_Dimensions._--Cephalis 0.02 long, 0.022 broad; thorax 0.14 long, 0.11
broad.

_Habitat._--Fossil in Barbados.



Genus 553. _Peromelissa_,[170] Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa) with three
divergent solid lateral wings.  Cephalis without horn.

The genus _Peromelissa_ differs from the preceding ancestral form,
_Micromelissa_, only in the absence of the cephalic horn, which is lost by
reduction.


1. _Peromelissa phalacra_, n. sp. (Pl. 57, fig. 11).

Shell smooth, with two joints of nearly equal size and similar ovate form.
Cephalis in the upper half hyaline, without pores; in the lower half with
four remote, transverse rows of irregular, roundish pores, decreasing in
size towards the hemispherical summit. Thorax with twelve transverse
{1237}rows of pores, the upper six rows three to four times as large as the
lower six rows. From its upper half diverge almost horizontally three
angular club-shaped wings, half as long as the shell.

_Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.06 long, 0.05
broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


2. _Peromelissa psilocrana_, n. sp.

Shell smooth, very similar to the preceding species in size and form, but
differing from it in the disposition of the irregular, roundish pores,
which are irregularly scattered, and in the form of the three wings, which
are slender, pyramidal, diverging downwards, and about as long as the
entire shell.

_Dimensions._--Cephalis 0.07 long, 0.06 broad; thorax 0.07 long, 0.06
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


3. _Peromelissa capito_, Haeckel.

  _Lithomelissa capito_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 78, Taf. iii. fig. 14.

Shell rough, with two joints of nearly equal size and similar ovate form.
Pores irregular, roundish, everywhere scattered. From the upper half of the
thorax arise three short conical wings, which are little curved and diverge
downwards (scarcely half as long as the breadth of the shell).

_Dimensions._--Cephalis 0.07 long, 0.06 broad; thorax 0.07 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


4. _Peromelissa calva_, n. sp. (Pl. 57, fig. 12).

Shell rough, with two ovate joints of somewhat different sizes. Pores
irregular, roundish, everywhere scattered. Thorax little larger than the
cephalis; from its upper half arise three short conical wings, diverging
downwardly or nearly horizontally.

_Dimensions._--Cephalis 0.06 long, 0.04 broad; thorax 0.07 long, 0.05
broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.



Genus 554. _Sethomelissa_,[171] Haeckel, 1881, Prodromus, p. 431.

_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa) with three
divergent latticed lateral wings. Cephalis with a horn (or a bunch of
horns).

The genus _Sethomelissa_ differs from the nearly allied _Micromelissa_ in
the fenestration of the three lateral wings, and may be derived either from
this genus by development of lattice-work connecting the three wings with
the shell, or perhaps from _Clathrocanium_ by closing the mouth.


{1238}1. _Sethomelissa hymenoptera_, n. sp.

Cephalis subspherical, thorny, with a bunch of three divergent, larger
apical spines. Thorax pear-shaped, with three broad, triangular, latticed
wings, the superior edge of which is a horizontal, straight, and stout
spine, nearly as long as the thorax. Pores irregular, roundish.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.11 long, 0.08 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 555. _Tetrahedrina_,[172] Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa) with a
three-sided pyramidal thorax, the three edges of which are prolonged into
three divergent, solid, terminal feet. Cephalis with a horn.

The genus _Tetrahedrina_, and the two following nearly allied genera, are
distinguished by the possession of three free, divergent, terminal feet,
projecting over the latticed mouth of the thorax. _Tetrahedrina_ may be
derived directly from _Dictyophimus_, by development of a horizontal
latticed mouth-plate from the middle part of the feet, the lower part of
which remains free. This genus, not noticed by Ehrenberg, is similar to his
_Lithochytris_, and common in the Barbados deposits.


1. _Tetrahedrina pyramidalis_, n. sp.

Shell three-sided pyramidal, smooth, with slight collar stricture. Length
of the two joints = 1 : 4, breadth = 1 : 4. Cephalis hemispherical, with
small, sparsely disposed pores, and a pyramidal horn of the same length.
Thorax with subregular, circular pores and three sharp edges, prolonged
into three divergent pyramidal feet of the same length.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.12 long, 0.12 broad.

_Habitat._--Fossil in Barbados.


2. _Tetrahedrina pyriformis_, n. sp.

Shell pear-shaped, rough, with distinct collar stricture. Length of the two
joints = 2 : 6, breadth = 2 : 5. Cephalis subspherical, with a conical horn
of the same length. Thorax with subregular, circular pores, ovate, at the
broad base with three pyramidal, widely divergent feet of the same length.
(Similar to _Lychnocanium tribulus_, Ehrenberg, 1875, _loc. cit._, pl. vii.
fig. 1, but with the mouth closed by a lattice-plate.)

_Dimensions._--Cephalis 0.04 diameter; thorax 0.12 long, 0.1 broad,

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


{1239}3. _Tetrahedrina quadricornis_, Haeckel.

  _Lithochytris triangula_, Bury, 1862, Polycystins of Barbados, pl. xix.
  figs. 4, 5, 6.

Shell pear-shaped, papillate, with slight collar stricture. Length of the
two joints = 1 : 5, breadth = 1 : 5. Cephalis subspherical, with a stout
conical horn twice the length. Thorax with irregular, roundish, lobulated
pores, with three conical, stout, divergent feet at the base, of the same
size and form as the cephalic horn.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.1 long, 0.1 broad.

_Habitat._--Fossil in Barbados.



Genus 556. _Sethochytris_,[173] Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa) with three
terminal latticed feet or hollow, fenestrated, divergent, basal apophyses
of the thorax. Cephalis with a horn.

The genus _Sethochytris_ differs from the preceding _Tetrahedrina_ in the
fenestration of the three basal feet, which form direct protrusions or
evaginations of the three basal corners of the pyramidal shell. It may be
derived from _Sethopera_ by centrifugal growth of the basal corners.


1. _Sethochytris triconiscus_, n. sp. (Pl. 57, fig. 13).

Shell rough, with deep collar stricture. Length of the two joints = 1 : 8,
breadth = 1 : 3. Cephalis spherical, with an oblique pyramidal horn of the
same length. Thorax campanulate, conical; its three basal corners prolonged
into three divergent, slender, hollow, fenestrated cones, twice as long as
the thorax, and ending in a stout pyramidal spine.

_Dimensions._--Cephalis 0.04 diameter, thorax 0.12 diameter, length of the
feet 0.2.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


2. _Sethochytris barbadensis_, Haeckel.

  _Lithochytris barbadensis_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 160, Taf. v. fig. 2.

Shell smooth, with slight collar stricture. Length of the two joints =
1 : 6, breadth = 1 : 4. Cephalis ovate, with a conical horn of half the
length. Thorax conical; its base prolonged into three divergent, hollow,
fenestrated cones, half as long as the thorax. Pores small, subregular,
circular.

_Dimensions._--Cephalis 0.025 diameter, thorax 0.1 diameter, length of the
feet 0.05.

_Habitat._--Fossil in Barbados.


{1240}3. _Sethochytris pyramis_, n. sp.

Shell smooth, with slight collar stricture. Length of the two joints =
1 : 8, breadth = 1 : 5. Cephalis ovate, with a conical horn of half the
length. Thorax pyramidal, with three sharp edges; its base prolonged into
three pyramidal, divergent, hollow, fenestrated feet, nearly as long as the
thorax. Pores regular, circular, double-contoured.

_Dimensions._--Cephalis 0.04 diameter; thorax 0.2 diameter, length of the
feet 0.15.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; also fossil
in Barbados.


4. _Sethochytris triangula_, Haeckel.

  _Lithochytris triangula_, Bury, 1862, Polycystins of Barbados, pl. xix.
  fig. 7.

Shell rough, with obliterated collar stricture (but distinct internal
collar septum). Length of the two joints = 1 : 6, breadth = 1 : 3. Cephalis
subspherical, with a stout conical horn of the same length. Thorax
pear-shaped, inflated; its base prolonged into three divergent, hollow,
fenestrated cones, about as long as the thorax. Pores regular, circular.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.09 diameter, length of the
feet 0.1.

_Habitat._--Fossil in Barbados.



Genus 557. _Clathrolychnus_,[174] Haeckel, 1881, Prodromus, p. 431.

_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa), with three
vertical, lateral latticed wings stretched between the apical horn and the
three terminal feet. The external lattice-work connecting the wings and
closing the mouth forms an arachnoidal mantle around the shell.

The genus _Clathrolychnus_ may be derived directly from _Clathrocorys_, by
development of an external arachnoidal mantle connecting the three wings
and the three feet, and enveloping the whole shell, closing at the same
time the basal mouth of the thorax by a fenestrated plate.


1. _Clathrolychnus araneosus_, n. sp. (Pl. 64, fig. 5).

Cephalis subspherical, with irregular, polygonal pores and a large
pyramidal horn of twice the length. Length of the two joints = 4 : 9,
breadth = 5 : 12. Thorax with three large triangular holes (twice as broad
as the cephalis) between the three pyramidal, divergent feet, which at the
distal end are connected by a narrow band of network, composed of two or
three rows of polygonal pores. The entire pyramidal shell is enveloped by a
very delicate web of irregular, polygonal {1241}meshes, closing also the
basal mouth. (In fig. 5 the greater part of the web is taken off to
demonstrate the large holes of the thorax). Only two feet are visible.

_Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.09 long, 0.12
broad.

_Habitat._--Central Pacific, Station 274, surface.


2. _Clathrolychnus periplectus_, n. sp. (Pl. 64, fig. 6).

Cephalis subspherical, with subregular, circular pores and a pyramidal horn
of the same length. Length of the two joints = 1 : 2, breadth = 1 : 3.
Thorax with three large elliptical holes between the three pyramidal,
divergent feet, which are connected at the distal end by a broad band of
network, composed of five to ten rows of polygonal pores. The entire
pyramidal shell is enveloped by a very delicate web, which on the sides is
composed of subregular, square meshes, and on the closed mouth of polygonal
meshes. (In fig. 6 only a part of the web is represented.)

_Dimensions._--0.04 long, 0.05 broad; thorax 0.08 long, 0.14 broad.

_Habitat._.--Central Pacific, Station 271, surface.



Family LXIII. #ANTHOCYRTIDA#, n. fam.

  _Sethophormida et Sethophænida_, Haeckel, 1881, Prodromus, p. 432, 433.

_Definition._--#Dicyrtida# multiradiata. (#Cyrtoidea# with a two-jointed
shell, divided by a transverse constriction into cephalis and thorax, and
bearing numerous--four to nine or more--radial apophyses.)

The family #Anthocyrtida#, composed of the Sethophormida and Sethophænida
of my Prodromus, comprises those #Cyrtoidea# in which the shell is
two-jointed and bears numerous radial apophyses. The two subfamilies differ
in the shape of the mouth, which in the Sethophormida is a simple, wide
opening; in the Sethophænida closed by a lattice-plate.

Numerous fossil and living forms of Anthocyrtida were described formerly by
Ehrenberg in his genera _Carpocanium_ and _Anthocyrtis_. These, however,
represent only a small part of the whole family, which exhibits a great
variety in the composition of the lattice-work and in the number of radial
beams. The number of species here described amounts to one hundred and
forty, and these are disposed in fourteen genera (twelve Sethophormida and
two Sethophænida).

The Sethophormida may be again divided into two different groups or tribes,
the _Sethamphorida_ and _Carpocanida_; in the former the thorax bears
numerous radial ribs, enclosed in its wall; in the latter these ribs have
disappeared, and only a corona of terminal feet is developed around the
mouth. The shell of the former is usually pyramidal, with a widely open
mouth; of the latter ovate, with a constricted mouth. The mouth of the
thorax becomes perfectly closed in the Sethophænida.

{1242}The majority of the Anthocyrtida may be derived from the Polyspyrida
(_Petalospyris_, &c.) by reduction of the cephalis and loss of the sagittal
ring, as was suggested by Bütschli (1882, _loc. cit._). But another part
may also have arisen from the Tripocyrtida, by interpolation of secondary
radial apophyses between the three primary perradial apophyses. The
cephalis in this family is developed in all possible degrees, from one of a
considerable size to one very much reduced. If it becomes perfectly lost,
the Cyrtocalpida arise.

_Synopsis of the Genera of Anthocyrtida._

  -------------------------------------------------------------------------
  I. Subfamily Sethophormida.
     Terminal mouth of the thorax a simple wide opening.
                            --------------------
     Radial ribs thorny (rarely smooth) prolonged into free terminal feet
        (cephalis commonly large, with one or more horns).
  -------------------------------------------------------------------------
  Shell flat, campanulate or nearly discoidal
   (cephalis without horn),                          558. _Sethophormis_.

  Shell ovate, with constricted mouth
   (without horn),                                   559. _Sethamphora_.

                   { Meshes of the network simple,   560. _Sethopyramis_.
                   {
  Shell slender    { Meshes fenestrated by
   pyramidal, with {  secondary latticework,         561. _Plectopyramis_.
   straight ribs.  {
                   { Meshes closed by spongy
                   {  framework,                     562. _Spongopyramis_.
  -------------------------------------------------------------------------
  Radial ribs thorny (rarely smooth) prolonged into free terminal feet
     (cephalis commonly large, with one or more horns).
  -------------------------------------------------------------------------
  Shell not enveloped by arachnoidal network,        563. _Acanthocorys_.

  Shell enveloped by arachnoidal network,            564. _Arachnocorys_.
  -------------------------------------------------------------------------
  No ribs in the thorax. Peristome with free terminal feet.
  -------------------------------------------------------------------------
                   {               { Six feet,       565. _Anthocyrtoma_.
                   { Feet          {
                   {  terminal,    { Nine feet,      566. _Anthocyrtis_.
  Cephalis         {  without      {
   well-developed  {  separate     { Twelve or more
   with an apical  {  peristome.   { feet,           567. _Anthocyrtium_.
   horn.           {
                   { Feet subterminal, outside the
                   {  constricted peristome,         568. _Anthocyrtidium_.

  Cephalis rudimentary, hidden in the upper
   part of the thorax, without horn,                 569. _Carpocanium_.
  -------------------------------------------------------------------------
  II. Subfamily Sethophænida. Terminal mouth closed by a lattice-plate.
  -------------------------------------------------------------------------
  Thorax with lateral apophyses (four to six or
   more wings),                                      570. _Sethophæna_.

  Thorax with terminal apophyses (four to six or
   more feet),                                       571. _Clistophæna_.



{1243}Subfamily 1. SETHOPHORMIDA, Haeckel, 1881, Prodromus, p. 432.

_Definition._--#Anthocyrtida# with the basal mouth of the shell open (vel
Dicyrtida multiradiata aperta).



Genus 558. _Sethophormis_, Haeckel,[175] 1881, Prodromus, p. 432.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous radial ribs in the wall of the flat and broad campanulate or
nearly discoidal thorax. Cephalis also flat and broad, cap-shaped without
horn.

The genus _Sethophormis_ comprises a great number of widely distributed and
large Dicyrtida, all agreeing in the flat cap-shaped or nearly discoidal
form of the thorax, which has constantly a very delicate network, and is
pierced by numerous radial beams. Four of these are commonly primary and
direct prolongations of the four cortinar rods in the collar septum, whilst
the others are secondary or interpolated ribs. _Sethophormis_ may be
derived either from the triradial _Lamprodiscus_ by multiplication of the
ribs (or interpolation of secondary ribs between the three primary), or
from _Halicalyptra_ by development of transverse rods connecting its
terminal feet, and forming a ribbed thorax. Corresponding to the number of
the ribs, we may distinguish as subgenera (separate genera in my Prodromus,
1881, p. 432) _Tetraphormis_ with four, _Pentaphormis_ with five,
_Hexaphormis_ with six, _Octophormis_ with eight, _Enneaphormis_ with nine,
and _Astrophormis_ with ten to twenty or more ribs. The cephalis bears no
horn, and is usually large, flat, cap-shaped or hemispherical.



Subgenus 1. _Tetraphormis_, Haeckel, 1881, Prodromus, p. 432.

_Definition._--Thorax with four radial ribs opposite in pairs in two
meridional planes, perpendicular to one another.  Collar septum with four
large pores.


1. _Sethophormis cruciata_, n. sp.

Cephalis very large, hemispherical with irregular, delicate network of
small square meshes. Thorax flatly campanulate, with delicate, regular
network of small hexagonal meshes. All bars very thin, thread-like. Four
stout radial thoracic ribs, crossed in pairs, lie in two meridional planes,
perpendicular to one another. Very similar to _Sethophormis aurelia_ (Pl.
55, figs. 3, 4), but not so flat, and with only four thoracic ribs.
Peristome or margin of the thoracic mouth smooth, circular.

_Dimensions._--Cephalis 0.04 long, 0.08 broad; thorax 0.12 long, 0.36
broad.

_Habitat._--Central Pacific, Station 271, surface.


{1244}2. _Sethophormis medusa_, n. sp.

Cephalis very large, flat, cap-shaped, with irregular, delicate network of
polygonal meshes. Thorax flat, campanulate, nearly hemispherical, with
delicate, irregular network of small polygonal meshes. All bars very thin,
thread-like. Four stout radial thoracic ribs, as in the preceding species.
Peristome denticulate.

_Dimensions._--Cephalis 0.03 long, 0.09 broad; thorax 0.15 long, 0.25
broad.

_Habitat._--North Pacific, Station 244, surface.



Subgenus 2. _Pentaphormis_, Haeckel, 1881, Prodromus, p. 432.

_Definition._--Thorax with five radial ribs, one of the three primary ribs
(the odd occipital rib) being simple, the two others (the paired lateral
ribs) forked.


3. _Sethophormis pentalactis_, n. sp. (Pl. 56, fig. 5).

Cephalis large, flat, hemispherical, with subregular, hexagonal pores.
Thorax flat, campanulate, nearly hemispherical; also with subregular,
hexagonal pores, and with five stout ribs. The three primary ribs of the
thorax are complete, and reach the peristome; the two secondary ribs (as
basal branches of the two lateral ribs) are incomplete and absent in the
distal half of the thorax. Peristome denticulate, with an elegant marginal
corona of small square pores and short conical spines.

_Dimensions._--Cephalis 0.03 long, 0.06 broad; thorax 0.1 long, 0.2 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


4. _Sethophormis asteriscus_, n. sp.

Cephalis large, flat, cap-shaped, with irregular polygonal pores. Thorax
flat, campanulate, with subregular, hexagonal pores, and five stout ribs.
The marginal distance between the two anterior (lateral) ribs is twice as
great as the distance between every two other ribs (the postero-lateral
ribs being basal branches of the antero-lateral ribs). Peristome with a
double corona of short, conical spines.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.06 long, 0.17
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


5. _Sethophormis astrodiscus_, n. sp.

Cephalis small, flatly vaulted, cap-shaped with irregular polygonal pores.
Thorax very flatly vaulted, nearly discoidal, with subregular hexagonal
pores, and five stout ribs. The marginal distance between all five ribs is
nearly equal. Peristome denticulate with an elegant corona of small square
pores and short conical thorns.

_Dimensions._--Cephalis 0.015 long, 0.035 broad; thorax 0.05 long, 0.2
broad.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.



{1245}Subgenus 3. _Hexaphormis_, Haeckel, 1881, Prodromus, p. 432.

_Definition._--Thorax with six radial ribs (three primary perradial and
three secondary interradial beams).


6. _Sethophormis hexalactis_, n. sp. (Pl. 56, fig. 6).

Cephalis large, hemispherical, with irregular, polygonal pores. Thorax
flatly campanulate, with subregular, hexagonal pores, and six stout radial
ribs; the lateral connected in pairs. (Fig. 6 exhibits the central part of
the shell, seen from below.) In the subcircular collar septum the two
anterior (jugular) meshes are much smaller than the two posterior
(cardinal) meshes. The odd anterior (sternal) rib is opposite to the
posterior (caudal) rib. The two paired ribs of each side (antero-lateral or
pectoral and  postero-lateral or ventral ribs) diverge from one common
point. In the specimen figured the left half of the thorax exhibited the
two regular ribs, and the right half three, a posterior accessory branch
being developed (transition to _Octophormis_). This specimen might indeed
be called _Heptaphormis heptalactis_.

_Dimensions._--Cephalis 0.02 long, 0.05 broad; thorax 0.08 long, 0.22
broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


7. _Sethophormis hexagonalis_, n. sp.

Cephalis small, flat, cap-shaped, with small, regular, hexagonal pores.
Thorax flatly conical, nearly discoidal, with larger pores of the same
form, and six stout, straight, prominent ribs. These arise at equal
distances from the six corners of the hexagonal base of the collar septum.
Peristome hexagonal, with a corona of short spines.

_Dimensions._--Cephalis  0.015 long, 0.04 broad; thorax 0.06 long, 0.24
broad.

_Habitat._--North Atlantic, Station 354, surface.



Subgenus 4. _Octophormis_, Haeckel.

_Definition._--Thorax with eight radial ribs, four secondary interradial
beams being interpolated between the four primary perradial beams of
_Tetraphormis_.


8. _Sethophormis octalactis_, n. sp.

Cephalis large, hemispherical, with irregular, polygonal pores. Thorax
flatly campanulate, with regular, hexagonal pores, and eight stout,
regularly-disposed, radial ribs reaching the margin at equal distances.
Four of these correspond to the four primary ribs of _Tetraphormis
cruciata_, and exhibit at their base a larger pair of basal pores,
surrounded by a semicircular ring (Pl. 70, fig. 5); the other four are
secondary, interpolated. Peristome circular, simple.

_Dimensions._--Cephalis 0.03 long, 0.06 broad; thorax 0.1 long, 0.22 broad.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.



{1246}Subgenus 5. _Enneaphormis_, Haeckel, 1881, Prodromus, p. 432.

_Definition._--Thorax with nine radial ribs, three of which are the primary
beams, the other six being secondary and interpolated.


9. _Sethophormis rotula_, n. sp. (Pl. 57, fig. 9).

  _Enneaphormis rotula_, Haeckel, 1881, Prodromus et Atlas, pl. lvii. fig.
  9.

Cephalis very large, flat, cap-shaped, trilobed, with irregular, polygonal
network. Horizontal collar-ring stout, hexagonal, with three larger and
three alternate smaller sides of half the length. From the middle of the
three larger sides arise three horizontal, centripetal, radial beams, which
are united in the centre of the collar-septum--the three primary cortinar
beams. These are prolonged outside into three centrifugal primary ribs of
the thorax. From the six corners of the collar-ring arise six other
secondary, thoracic ribs, equal in size and similar in form to the three
primary. Each of these nine equal, straight ribs of the thorax is thickened
towards the distal end, and bears at equal distances five pairs of opposite
(tangential) lateral branches. The opposite branches of the neighbouring
spines become united, and lie nearly horizontally in one plane, so that the
flat, discoidal thorax is like a nine-angled wheel with nine equally
distant spokes and five concentric, nine-angled rings.

_Dimensions._--Cephalis 0.12 diameter, thorax 0.36 diameter.

_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.


10. _Sethophormis triloba_, n. sp.

Cephalis large, hemispherical, distinctly trilobed, with dense, irregular,
polygonal network. From the centre of its top diverge three stout arches or
semilunar rods, which are curved downwards, and unite with the three
horizontal, radial beams of the collar-septum inside the collar-ring. These
three parietal arches of the cephalis are much stronger than in the similar
preceding species (Pl. 57, fig. 9), and between them are placed three
vaulted bosoms of the cephalis. The collar-ring and the thorax are of the
same form as in the preceding, but possess only four concentric,
nine-angled rings.

_Dimensions._--Cephalis 0.05 long, 0.08 broad; thorax 0.24 diameter.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


11. _Sethophormis enneastrum_, n. sp.

Cephalis very large, flat, cap-shaped, with hexagonal base, trilobed, of
similar form and structure to the two preceding species. The flat,
discoidal thorax has also the same form, with nine stout ribs and five
concentric, nine-angled rings; its forty-five large meshes, however, are
not so simple {1247}as these (Pl. 57, fig. 9), but are subdivided into
irregular, smaller meshes by interpolated radial beams connecting the
concentric rings.

_Dimensions._--Cephalis 0.1 diameter, thorax 0.3 diameter.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.


12. _Sethophormis arachnium_, n. sp.

Cephalis very large, flat, cap-shaped, trilobed, with hexagonal base, of
the same structure as in the three preceding species. The flat discoidal
thorax is also similar, and has the same structure as in the preceding
species (Pl. 57, fig. 9); but the number of concentric, nine-angled rings
is raised from five to eight, and in its outer part nine secondary radial
beams are interpolated between the nine primaries, so that the peristome
has not nine but eighteen corners.

_Dimensions._--Cephalis 0.08 diameter, thorax 0.4 diameter.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


13. _Sethophormis enneactis_, n. sp.

Cephalis small, hemispherical, with small, irregular, polygonal pores.
Thorax flatly pyramidal, nearly discoidal, with nine prominent, stout ribs,
which are connected by numerous (twelve to sixteen) horizontal, nine-angled
rings. In the outer half of the thorax there are nine weaker secondary ribs
interpolated between the nine stronger primaries, and eighteen shorter and
feebler tertiary ribs between the former and the latter. Peristome
denticulated, nine-angled.

_Dimensions._--Cephalis 0.03 diameter, thorax 0.08 long, 0.24 broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


14. _Sethophormis eupilium_, n. sp. (Pl. 56, fig. 9).

  Sethopyramis eupilium, Haeckel, 1882, Atlas, pl. lvi. fig. 9.

  Craspedilium eupilium, Haeckel, 1878, Manuscript.

Cephalis very small, hemispherical, hyaline, without pores. Thorax flatly
pyramidal, with nine concave, triangular faces and nine little curved,
stout, radial beams. Between these are interpolated numerous incomplete
secondary beams, which are absent in the apical part of the thorax. The
radial beams being connected by numerous (thirty to forty or more)
horizontal, ring-like threads, a delicate arachnoidal network with small,
quadrangular pores is produced. Peristome nine-angled, with a peculiar
vertical gallery, composed of four horizontal, parallel, nine-angled rings,
which are connected by numerous vertical, parallel bars, therefore with
three transverse rows of square pores. This peculiar species is very
different from the preceding and may represent a separate genus,
_Craspedilium_.

_Dimensions._--Cephalis 0.01 diameter, thorax 0.1 long, 0.25 broad.

_Habitat._--Central Pacific, Station 271, surface.



{1248}Subgenus 6. _Astrophormis_, Haeckel.

_Definition._--Thorax with a variable number of radial ribs (twelve to
twenty or more).


15. _Sethophormis aurelia_, n. sp. (Pl. 55, figs. 3, 4).

  _Leptarachnium aurelia_, Haeckel, 1879, Manuscript et Atlas.

Cephalis large, nearly hemispherical, with irregular, delicate network of
small square meshes. Collar-septum with four large meshes, separated by a
cross of four bars, opposite in pairs. Thorax flatly campanulate, with
delicate, subregular, hexagonal meshes, and twenty-four prominent radial
ribs; four of these are primary or perradial (centrifugal prolongations of
the four bars of the collar-septum); four others are interradial or
secondary, alternating with the former at angles of 45°; sixteen others are
adradial or tertiary, interpolated between the first and second more or
less irregularly. In some specimens the disposition of the twenty-four ribs
was more regular, in others more irregular, than in the specimen figured
(figs. 3, 4). The central capsule (fig. 4) exhibits a flat, cap-shaped part
with the nucleus (enclosed in the cephalis), and four large, pear-shaped
lobes protruded through the four large collar holes (somewhat deformed in
the preparation figured). The wall of the thorax exhibits at the base four
larger, nearly semicircular pores, bisected by the four primary thoracic
ribs. Peristome with twenty-four indentations (between the prominent distal
ends of the twenty-four ribs), often more distinct than in the specimen
figured.

_Dimensions._--Cephalis 0.03 long, 0.08 broad; thorax 0.1 to 0.2 long, 0.4
to 0.6 broad.

_Habitat._--Central Pacific, Station 263 to 274, depth 2350 to 2925
fathoms.


16. _Sethophormis dodecaster_, n. sp. (Pl. 56, fig. 12).

Cephalis small, flatly cap-shaped, with irregular, small, roundish pores.
Thorax flatly conical, nearly of the same shape as in the preceding
species, but only with twelve prominent ribs; four primary or perradial
ribs (as prolongations of the four crossed cortinar bars), and eight
adradial ribs interpolated between the former, and arising at some distance
from the collar ring. Peristome with twelve prominent pointed lobes
(supported by the distal ends of the twelve ribs), and with twelve
semicircular bosoms between them. (The specimen figured is young and not
fully developed.)

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.1 long, 0.3 broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.


17. _Sethophormis umbrella_, n. sp. (Pl. 70, figs. 4, 5).

Cephalis large, flatly cap-shaped, with irregular, small polygonal meshes.
Thorax flat, umbrella-shaped, with subregular, hexagonal meshes, and
sixteen strong radial ribs. Four of these are perradial, and centrifugal
prolongations of the four crossed collar beams; four others are
interradial, and {1249}arise, alternating with the former, directly from
the horizontal collar ring; eight ribs are adradial or tertiary, and arise
in pairs from the four large perradial basal arches of the thorax, which
become bisected by the four primary ribs. Peristome irregularly
denticulate.

_Dimensions._--Cephalis 0.02 long, 0.06 broad; thorax 0.12 long, 0.32
broad.

_Habitat._--North Pacific (off Japan), Stations 236 to 239, surface.


18. _Sethophormis floscula_, n. sp.

Cephalis small, hemispherical, with subregular, small hexagonal pores.
Thorax flatly conical, with larger hexagonal meshes and twenty-four ribs;
four of these are perradial and prolongations of the four collar bars; four
interradial arise from the collar ring between the former, alternating with
them. Each of these eight main ribs gives off two more or less irregular,
lateral branches (one at each side), altogether sixteen. The thorax is
similar to _Cladarachnium ramosum_ (Pl. 55, fig. 5), whilst the cephalis is
quite different. Peristome with twenty-four prominent triangular lobes.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.1 long, 0.4 broad.

_Habitat._--South Atlantic, Station 325, surface.


19. _Sethophormis leptoscenium_, n. sp.

Cephalis very small, spherical, with few small, circular pores. Thorax
flatly conical or tent-shaped, with concave lateral outlines, small
hexagonal meshes, and numerous (thirty to forty or more) strong, little
curved, simple radial ribs. Peristome nearly circular, with a corona of
small, irregular, conical spines.

_Dimensions._--Cephalis 0.015 diameter; thorax 0.07 long, 0.26 broad.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.


20. _Sethophormis leptopilium_, n. sp.

Cephalis very small, subspherical, hyaline, without pores. Thorax flatly
conical or hat-shaped, with concave lateral outlines, and a very delicate
network of small square meshes (similar to _Litharachnium araneosum_, Pl.
55, fig. 8). This is supported by thirty-two curved radial ribs, four of
which are primary, four secondary, and the other twenty-four interpolated.
Peristome horizontally expanded and little recurved, like the reflexed brim
of a hat.

_Dimensions._--Cephalis 0.12 diameter; thorax 0.08 long, 0.24 broad.

_Habitat._--South Pacific, Station 291, depth 2250 fathoms.



Genus 559. _Sethamphora_,[176] n. gen.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous curved ribs in the wall of the ovate thorax, the small mouth of
which is constricted. Cephalis without horn.

{1250}The genus _Sethamphora_ differs from the preceding _Sethophormis_,
and from the next following ribbed Sethophormida, mainly in the small, more
or less constricted mouth; therefore the thorax is more or less ovate, and
its ribs curved, with the convexity external. Sethophormis may be divided
into two different subgenera, _Dictyoprora_ and _Cryptocephalus_; in the
former the cephalis is perfectly free and well developed, in the latter it
is more or less hidden in the uppermost part of the thorax (like
_Carpocanium_).



Subgenus 1. _Dictyoprona_, Haeckel, 1881, Prodromus, p. 430.

_Definition._--Cephalis large, perfectly free, not hidden in the thorax.


1. _Sethamphora hexapleura_, n. sp.

Shell ovate, smooth, with distinct collar stricture. Length of the two
joints = 3 : 11, breadth = 5 : 10. Cephalis large, free, hemispherical,
with small circular pores. Thorax truncate, ovate, with six strong curved
ribs, and six large triangular meshes between them in the upper half; five
smaller pores between every two ribs in the lower half (in three tiers);
therefore, together, thirty-six thoracic meshes. Mouth strongly
constricted, smooth, only one-third as broad as the thorax.

_Dimensions._--Cephalis 0.03 long, 0.05 broad; thorax, 0.11 long, 0.1
broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


2. _Sethamphora enneapleura_, n. sp.

Shell subovate, smooth, with slight collar stricture. Length of the two
joints = 3 : 9, breadth = 4 : 8. Cephalis large, hemispherical, free, with
small circular pores. Thorax inflated, ovate, with nine strong curved ribs,
which are connected by five transverse circular rings at equal distances.
Forty-five rounded, squarish, large meshes between them, in five transverse
and nine longitudinal rows. Mouth constricted, smooth, half as broad as the
thorax.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.08
broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


3. _Sethamphora dodecapleura_, n. sp.

Shell urceolate, smooth, with sharp collar stricture. Length of the two
joints = 3 : 9, breadth = 5 : 9. Cephalis flat, cap-shaped, free, with
twelve ribs, and very small pores between them. Thorax thick-walled,
inflated, with subcylindrical cavity, and twelve prominent sharp ribs,
alternating with twelve longitudinal rows of very small circular pores
(eight pores in each row). Mouth constricted, half as broad as the thorax.

_Dimensions._--Cephalis 0.03 long, 0.05 broad; thorax 0.09 long, 0.09
broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.


{1251}4. _Sethamphora mongolfieri_, Haeckel.

  _Eucyrtidium mongolfieri_, Ehrenberg, 1854, Mikrogeol., Taf. xxxiv. fig.
  18; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 72, Taf. x. fig. 3.

Shell urceolate, smooth, with distinct collar stricture. Length of the two
joints = 2 : 9, breadth = 3 : 7. Cephalis campanulate, with eighteen ribs
and small pores. Thorax nearly ellipsoidal, with eighteen prominent ribs,
and eighteen longitudinal rows of regular circular pores between them
(eight pores in each row; therefore 144 pores altogether). Mouth
constricted, only one-third as broad as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.07
broad.

_Habitat._--Fossil in Barbados.


5. _Sethamphora costata_, n. sp. Pl. 62, fig. 3.

Shell urceolate, smooth, very similar to the preceding species; also with
eighteen longitudinal ribs, but differing in the larger size of the
cephalis and its pores, and in the more slender and ovate form of the
thorax. Length of the two joints = 5 : 10, breadth = 5 : 8. Pores of the
cephalis more numerous. Mouth half as broad as the thorax.

_Dimensions._--Cephalis 0.05 long, 0.05 broad; thorax 0.1 long, 0.08 broad.

_Habitat._--Central Pacific, Stations 265 to 274, depth 2350 to 2925
fathoms.


6. _Sethamphora serrata_, n. sp.

Shell ovate, spinulate, without external collar stricture. Length of the
two joints = 1 : 6, breadth = 2 : 4. Cephalis flat, cap-shaped, with small
circular pores. Thorax ovate, truncate, with eighteen serrate longitudinal
ribs, alternating with eighteen longitudinal rows of short and broad rather
oblong pores (twenty to thirty pores in each row). Mouth strongly
constricted, only one-fourth as broad as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.08
broad.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


7. _Sethamphora ampulla_, Haeckel.

  _Eucyrtidium ampulla_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 15;
  Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 72, Taf. x. figs. 11, 12.

Shell broad, urceolate, spiny, with sharp collar stricture. Length of the
two joints = 1 : 4, breadth = 1 : 5. Cephalis subspherical, with few small
pores (in figs. 12_a_ and 12_b_ of Ehrenberg, _loc. cit._, broken off, so
that the four pores of the cortinar septum appear). Thorax inflated,
bottle-shaped, with twenty prominent, sharply dentate ribs, alternating
with twenty longitudinal rows of circular pores (about eight pores in each
row). Mouth flat, constricted, one-third as broad as the thorax.

_Dimensions._--Cephalis 0.025 long, 0.03 broad; thorax 0.1 long, 0.14
broad.

_Habitat._--Fossil in Barbados.


{1252}8. _Sethamphora aërostatica_, Haeckel.

  _Podocyrtis aërostatica_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 80, Taf. xvi. fig. 4.

Shell broad, urceolate, smooth, with sharp collar stricture. Length of the
two joints = 2 : 6, breadth = 3 : 8. Cephalis hemispherical, large, with
few pores (broken off in fig. 4_a_ of Ehrenberg, so that the six collar
pores appear). Thorax inflated, bottle-shaped, with twenty-two to
twenty-four smooth prominent ribs, alternating with the some number of
longitudinal rows of small circular pores. Mouth very small, strongly
constricted, scarcely as broad as the cephalis, with three short teeth.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08
broad.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Cryptocephalus_, Haeckel, 1881, Prodromus, p. 430.

_Definition._--Cephalis more or less hidden in thorax, being partly
enveloped by its uppermost part.


9. _Sethamphora microstoma_, n. sp. (Pl. 57, fig. 5).

  _Cryptoprora microstoma_, Haeckel, Atlas, pl. lvii., fig. 5.

Shell ovate, smooth, without external collar stricture. Length of the two
joints = 1 : 6, breadth = 2 : 4. Cephalis flat, cap-shaped, without ribs,
with small circular pores. Thorax ovate, with twenty-four prominent ribs,
alternating with deep longitudinal furrows, each of which contains a series
of about fifteen small circular pores. Mouth very small, representing a
short cylindrical tube, which is only one-eighth as broad as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.08
broad.

_Habitat._--Western Tropical Pacific, Station 220, depth 1100 fathoms.


10. _Sethamphora favosa_, n. sp, (Pl. 57, fig. 4).

  _Cryptocephalus favosus_, Haeckel, 1881, Prodromus, p. 430.

Shell ovate, dimply. Length of the two joints = 1 : 5, breadth = 1 : 5.
Cephalis subspherical, small, completely hidden in the thickened top of the
thorax (but very distinct in the longitudinal section). Thorax ovate, with
twenty-five to thirty longitudinal ribs, alternating with the same number
of longitudinal furrows, each of which contains ten to twelve circular,
hexagonally framed pores. In the smooth wall of the peristome only twelve
triangular ribs are visible. Mouth constricted, one-third as broad as the
thorax.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.1 long, 0.09 broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



{1253}Genus 560. _Sethopyramis_,[177] Haeckel, 1881, Prodromus, p. 432
(sensu emendato !)

_Definition_.--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous straight or slightly curved radial ribs in the wall of the
pyramidal thorax. Network simple. Cephalis commonly without horn.

The genus _Sethopyramis_ and the four following genera form together a
peculiar small group (Sethopyramida), characterised by the slender
pyramidal shell, in the wall of which numerous (six to nine or more) radial
ribs are enclosed. These ribs may be regarded as the terminal feet of a
_Calpophæna_ or _Halicalyptra_, which become connected by transverse bars.
_Sethopyramis_ may be derived also directly from _Patagospyris_ by loss of
the primary sagittal ring and reduction of the cephalis.



Subgenus 1. _Sestropyramis_, Haeckel.

_Definition_.--Pyramidal shell with six radial main beams (sometimes also
five or seven, as individual varieties).


1. _Sethopyramis scalaris_, Haeckel.

  _Cornutella scalaris_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. ii. fig. 1.

Shell smooth, slenderly pyramidal, hexagonal. Cephalis large, subglobular,
hyaline, without pores (or with very small and scarce pores). Thorax with
six straight (or little curved) stout longitudinal ribs or radial beams,
which are connected by twenty to thirty complete, hexagonal, horizontal
rings. The large meshes so produced are regular, square, their length and
breadth equally and gradually increasing towards the mouth.

_Dimensions_.--Cephalis 0.04 diameter; thorax (with twenty-four transverse
rings) 0.4 long, 0.15 broad at the mouth.

_Habitat_.--Fossil in Barbados.


2. _Sethopyramis hexalactis_, n. sp.

Shell thorny, of the same form as, and similar structure to, the preceding
species, but differing in the spiny surface and the smaller subglobular
cephalis, which bears small circular pores and an oblique conical horn
twice the length. The whole surface is covered with short conical thorns.

_Dimensions_.--Cephalis 0.02 diameter; thorax (with twenty transverse
rings) 0.25 long, 0.1 broad.

_Habitat_.--Central Pacific, Station 268, depth 2900 fathoms.



Subgenus 2. _Cephalopyramis_, Haeckel, 1881, Prodromus, p. 432.

_Definition._--Pyramidal shell with nine radial main beams (sometimes also
eight or ten, as individual varieties).


{1254}3. _Sethopyramis enneactis_, n. sp. (Pl. 56, fig. 7).

  _Cephalopyramis enneactis_, Haeckel, 1881, Prodromus et Atlas, pl. lvi.
  fig. 7.

Shell smooth, slender, pyramidal. Cephalis large, ovate, with pointed apex,
nearly hyaline, with very few and small scattered pores. Thorax very
slenderly pyramidal, with straight lateral outlines, and nine stout and
straight radial beams, which are connected by fifteen to twenty horizontal
complete rings. Meshes subregular, square, simple, without secondary
network; their length and breadth equally increasing towards the mouth.

_Dimensions._--Cephalis 0.05 long, 0.03 broad; thorax (with twenty
transverse rings) 0.24 long, 0.1 broad at the mouth.

_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.


4. _Sethopyramis quadrata_, n. sp. (Pl. 54, fig. 2).

Shell smooth, slenderly pyramidal, very similar in form and structure to
the preceding species; differing from it in the rudimentary cephalis, which
is very small, hemispherical, with few small porules. The three internal
cortinar bars of the collar stricture are present; when they become lost
this species passes over into _Bathropyramis quadrata_ (Pl. 54, fig. 1).

_Dimensions._--Cephalis 0.01 long, 0.02 broad; thorax (with ten transverse
rings) 0.15 long, 0.1 broad at the mouth.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


5. _Sethopyramis quadratella_, Haeckel.

  _Cornutella quadratella_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 68, Taf. ii. fig. 2.

  _Litharachnium quadratella_, Bütschli, 1882, Zeitschr. f. wiss. Zool.,
  vol, xxxvi. p. 540, Taf. xxxiii. fig. 37.

Shell smooth, broadly pyramidal. Cephalis ovate, small, blunt, hyaline,
with very few and small pores (in the figure of Ehrenberg broken off).
Thorax broadly pyramidal, with straight lateral outlines, and nine stout
and straight radial beams, which are connected by eight to twelve
horizontal complete rings. Meshes in the upper half regular, square, in the
lower half broad, rectangular (in the tenth transverse row twice as broad
as long).

_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax (with ten transverse
rings) 0.15 long, 0.15 broad.

_Habitat._--Fossil in Barbados.


6. _Sethopyramis trapezoides_, n. sp.

Shell smooth, broadly pyramidal. Cephalis large, ovate, hyaline, without
pores; its collar septum exhibits distinctly the four collar pores (two
larger cardinal and two smaller jugular pores). {1255}Thorax broad,
pyramidal, with slightly concave lateral outlines and nine (sometimes eight
or ten) curved ribs, which are connected by eighteen to twenty-four
complete transverse rings. The large meshes, so produced, have the form of
a parallel trapezoid, and are in the eighth transverse row three times as
broad as long. (Differs from _Bathropyramis trapezoides_, Pl. 54, fig. 3,
mainly by the possession of a well developed cephalis).

_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax (with eighteen rings)
0.32 long, 0.24 broad.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.


7. _Sethopyramis spinosa_, n. sp.

Shell thorny, slender, pyramidal. Cephalis small, subspherical, with few
small pores and a straight, vertical, conical horn twice the length. Thorax
with nine straight ribs, which are connected by sixteen to twenty complete
transverse nine-angled rings. The large meshes so produced are subregular,
square. From each nodal point a short conical spine arises. (Differs from
the similar _Bathropyramis spinosa_, Pl. 54, fig. 4, by the development of
the cephalis and the simple pointed, unforked spines.)

_Dimensions._--Cephalis 0.03 diameter; thorax (with sixteen rings) 0.2
long, 0.12 broad.

_Habitat._--Central Pacific, Station 263, depth 2650 fathoms.


8. _Sethopyramis hexagonalis_, n. sp.

Shell papillate, slender, pyramidal. Cephalis small, hemispherical, with a
straight conical horn twice the length, and small circular pores. Thorax
conical, with slightly convex outlines and nine stout, somewhat curved ribs
in zig-zag form, which are connected by ten to twelve interrupted
transverse bars. From each nodal point a small conical papilla arises. The
large meshes so produced are regular, hexagonal, gradually increasing in
size towards the mouth.

_Dimensions._--Cephalis 0.03 diameter; thorax (with twelve transverse rows
of meshes) 0.18 long, 0.12 broad.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.


9. _Sethopyramis cyclomma_, n. sp.

Shell thorny, slender, pyramidal. Cephalis large, subspherical, with
numerous very small circular pores, and a small conical horn of the same
length. Thorax similar in form and structure to that of the preceding
species; but each hexagonal mesh is provided with a very thin circular
hyaline ring (like a diaphragm), so that the openings are not hexagonal,
but circular. From each nodal point a short pointed conical or slightly
forked spine arises.

_Dimensions._--Cephalis 0.02 diameter; thorax (with ten transverse rows of
meshes) 0.18 long, 0.14 broad.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.



{1256}Subgenus 3. _Actinopyramis_, Haeckel.

_Definition._--Pyramidal shell with twelve or more radial beams (commonly
twelve to twenty-four, sometimes forty or more).


10. _Sethopyramis dodecalactis_, n. sp.

Shell smooth, slender, pyramidal. Cephalis small, spherical, hyaline, with
a short conical horn. Thorax with twelve radial ribs in the upper half,
between which twelve others are interpolated in the lower half. These are
connected by twenty to twenty-four complete transverse rings. The meshes so
produced are subregular, rectangular.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.6 long, 0.2 broad.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.


11. _Sethopyramis bicornis_, n. sp.

Shell spiny, slender, pyramidal. Cephalis small, spherical, hyaline, with
two divergent conical horns, the major (occipital) three times and the
minor (frontal) twice as long. Thorax slender, pyramidal, campanulate,
thorny, with twenty to thirty radial beams, which are little curved, convex
in the upper, concave in the lower half, and connected by numerous
interrupted transverse bars. Meshes in the upper third rounded, in the
lower two-thirds quadrangular, of very different sizes. Surface covered
with spinules.

_Dimensions._--Cephalis 0.02 diameter; thorns 0.9 long, 0.4 broad.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


12. _Sethopyramis maxima_, n. sp.

Shell smooth, slender, pyramidal. Cephalis small, spherical, with few small
pores, and a stout, vertical, conical horn twice the length. Thorax very
prolonged, conical, with straight lateral outlines and numerous (twenty to
fifty) radial beams (in the upper third twelve, in the middle third
twenty-four, in the lower third forty to fifty, by interpolation); they are
connected by very numerous interrupted transverse bars. Meshes subregular,
quadrangular. Surface smooth.

_Dimensions._--Cephalis 0.02 diameter; thorax 1.05 long, 0.45 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Genus 561. _Plectopyramis_,[178] Haeckel, 1881, Prodromus, p. 432.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous straight or slightly curved radial ribs in the wall of the
pyramidal thorax. Network double, the large primary meshes being
fenestrated by fine secondary network. Cephalis commonly without horn.

{1257}The genus _Plectopyramis_ differs from the preceding _Sethopyramis_,
its ancestral form, only in the peculiar double fenestration of the shell,
the large primary meshes of which are separated by strong bars, and filled
up by a very delicate arachnoidal network, composed of small pores and very
thin threads between them. This double lattice-work often exhibits a very
remarkable regularity. As in the preceding genus, the number of radial ribs
is commonly six or nine, rarely twelve to twenty or more.



Subgenus 1. _Hexapleuris_, Haeckel.

_Definition._--Pyramidal shell with six radial main beams (sometimes five
or seven in individual varieties).


1. _Plectopyramis magnifica_, Haeckel.

  _Polycystina magnifica_, Bury, 1862, Polycystins of Barbados, pl. xi.
  fig.

Shell smooth, slender, pyramidal. Cephalis large, ovate, pointed, separated
from the thorax by a very deep collar stricture, with few irregular pores.
Thorax with six strong and straight radial beams, which are connected by
about twenty horizontal, hexagonal rings. The large meshes so produced are
regular, square, and filled up by an extremely delicate secondary
arachnoidal network, composed of regular square pores (as in Pl. 54, figs.
7, 8).

_Dimensions._--Cephalis 0.06 long, 0.04 broad; thorax (with twenty
transverse rings) 0.4 long, 0.12 broad.

_Habitat._--Fossil in Barbados.


2. _Plectopyramis hexapleura_, n. sp.

Shell thorny, slender, pyramidal. Cephalis large, ovate, blunt, with deep
collar stricture. Thorax with six strong and straight radial beams, which
are connected by numerous (twenty to thirty) interrupted transverse bars.
The large meshes so produced are irregular, quadrangular, and filled up by
irregular, delicate, secondary network, with small polygonal pores.

_Dimensions._--Cephalis 0.05 long, 0.03 broad; thorax 0.3 long, 0.1 broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.



Subgenus 2. _Enneapleuris_, Haeckel.

_Definition._--Pyramidal shell with nine radial main beams (sometimes eight
or ten in individual varieties).


{1258}3. _Plectopyramis dodecomma_, n. sp. (Pl. 54, fig. 6).

Shell smooth, slenderly pyramidal, with straight outlines. Cephalis
conical, obtuse, with thirty-six small square pores (in nine divergent
longitudinal rows, each of four pores). Collar septum (between cephalis and
thorax) with four distinct collar pores. Thorax pyramidal, with nine very
stout and straight angular radial beams, which are connected by ten to
fifteen broad horizontal nine-angled rings. Each of the large regular,
square meshes so produced contains a very delicate fenestration, with
twelve regular, square pores, separated by two transverse and three
longitudinal crossed threads. A very regular and remarkable structure.

_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax (with ten rings) 0.2
long, 0.15 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


4. _Plectopyramis quadratomma_, n. sp.

Shell smooth, slenderly pyramidal. Cephalis large, ovate, hyaline, with few
very small basal pores and deep collar stricture. Thorax pyramidal, with
straight outline, and nine very stout and straight radial beams, which are
connected by fifteen to twenty horizontal nine-angled rings. Each of the
large regular, square meshes so produced is filled up by a very delicate
arachnoidal network, with very numerous and small square pores (as in the
similar _Cinclopyramis infundibulum_, Pl. 54, fig. 7, which differs in the
loss of the cephalis).

_Dimensions._--Cephalis 0.05 long, 0.03 broad; thorax (with fifteen rings)
0.32 long, 0.2 broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


5. _Plectopyramis trapezomma_, n. sp. (Pl. 54, fig. 8).

Shell smooth, broadly pyramidal, with concave lateral outlines. Cephalis
hemispherical, small, with numerous small, circular pores. Thorax
pyramidal, with nine stout, concavely curved radial beams, which are
connected by twelve to sixteen horizontal nine-angled rings. The large
meshes so produced are in the upper half square, in the lower half parallel
trapezoid (in the fifteenth ring three times as broad as long), and filled
up by a secondary arachnoidal network, with very numerous and small square
pores.

_Dimensions._--Cephalis 0.015 long, 0.025 broad; thorax (with fifteen
rings) 0.22 long, 0.2 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.


6. _Plectopyramis polygonomma_, n. sp.

Shell smooth, pyramidal, very similar to the preceding species; differing
from it in the irregular shape of the delicate polygonal (not tetragonal)
secondary network, filling up the large rectangular meshes. The cephalis is
larger, hyaline, pear-shaped, pointed, without pores, with a deep collar
stricture. The nine radial beams of the thorax are less concave.

_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax (with fifteen rings)
0.3 long, 0.22 broad.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


{1259}7. _Plectopyramis heteromma_, n. sp.

Shell smooth, slenderly pyramidal, with concave outlines. Cephalis very
small, subspherical, with a small oblique, conical horn, and very small,
scarce circular pores. Thorax with nine stout concavely curved radial
beams, which are connected by numerous (thirty to fifty or more)
interrupted transverse bars. The large irregular meshes so produced are
filled up by irregular, polygonal, delicate lattice-work.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.6 long, 0.3 broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


8. _Plectopyramis serrata_, n. sp.

Shell thorny, slenderly pyramidal, with straight outlines. Cephalis very
small, spherical, with a long oblique, conical horn, and very small
circular pores. Thorax with nine stout, straight, regularly serrate ribs or
radial beams, which are connected by numerous (twenty to thirty or more)
interrupted transverse bars. The latter, being crossed by intercalated and
interrupted irregular radial beams, produce a subregular secondary network
of rectangular meshes of different sizes.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax, 0.3 long, 0.2 broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.


9. _Plectopyramis fenestrata_, Haeckel.

  _Pyramis fenestrata_, Bury, 1862, Polycystins of Barbados, pl. xxi. fig.
  8.

Shell thorny, broadly pyramidal, with straight outlines. Cephalis very
small, spherical, hyaline. Thorax with nine stout, spinulate, straight ribs
or radial beams, which are connected by ten to fifteen transverse bars,
which in the upper half are complete rings, in the lower half interrupted,
and crossed by irregularly intercalated radial beams. Meshes therefore
irregular, quadrangular. All the bars are thorny.

_Dimensions._--Cephalis 0.01 diameter; thorax 0.2 long, 0.16 broad.

_Habitat._--Tropical Atlantic.


10. _Plectopyramis furcata_, n. sp.

Shell spiny, slenderly pyramidal, with straight outlines. Cephalis small,
spherical, with few small pores. Thorax with nine stout and straight
spinulate ribs, which are connected by a variable number of irregular
interrupted transverse bars; the large quadrangular meshes so produced are
filled up by irregular delicate network. The entire surface of the thorax
is covered with short forked spines.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.3 long, 0.2 broad.

_Habitat._--Indian Ocean (Zanzibar), Pullen, depth 2200 fathoms.



{1260}Subgenus 3. _Polypleuris_, Haeckel.

_Definition._--Pyramidal shell with numerous (twelve or more) radial main
beams (commonly twelve to eighteen, sometimes twenty to thirty or more).


11. _Plectopyramis polypleura_, n. sp. (Pl. 56, fig. 8).

Shell smooth, slenderly conical, with straight outlines. Cephalis small,
subspherical, with very small dot-like pores, and an oblique conical horn
twice the length. Thorax with numerous (twenty to thirty) divergent
longitudinal ribs; usually twelve of these radial beams appear as stronger,
primary main ribs, and twelve to eighteen other as secondary, feebler,
interpolated ribs. They are crossed by numerous (twenty to forty or more)
horizontal rings. The large meshes so produced are quadrangular, and partly
filled up by a very delicate secondary network, with small square pores.

_Dimensions._--Cephalis 0.03 diameter; thorax 0.36 long, 0.24 broad.

_Habitat._--Central Pacific, Station 267, depth 2700 fathoms.


12. _Plectopyramis lagena_, n. sp.

Shell smooth, wine-bottle shaped, or slenderly conical-campanulate, with
bent outlines, which are concave in the upper, convex in the lower half.
Cephalis very small, spherical, hyaline, without pores. Thorax with
twenty-four radial ribs, twelve stronger primary, alternating with twelve
feebler secondary. They are crossed by interrupted transverse bars. The
irregular quadrangular meshes so produced are filled up by a delicate,
irregular, secondary network.

_Dimensions._--Cephalis 0.02 diameter; thorax 0.5 long, 0.3 broad.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.



Genus 562. _Spongopyramis_,[179] n. sp.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous straight or slightly curved radial ribs in the wall of the
pyramidal thorax. Network spongy. Cephalis commonly without horn.

The genus _Spongopyramis_ has arisen from _Sethopyramis_ by development of
an irregular spongy framework around the lattice-shell, and is one of the
small number of #Cyrtoidea# in which the shell-wall exhibits a spongy
structure. In both observed species the cephalis is small, but evident.


{1261}1. _Spongopyramis spongiosa_, n. sp. (Pl. 56, fig. 10).

  _Plectopyramis spongiosa_, Haeckel, 1881, Prodromus et Atlas, _loc. cit._

Shell partly or entirely enveloped by spongy framework, slender, pyramidal,
with rather straight outlines. Cephalis very small, ovate, hyaline. Thorax
with nine very stout and nearly straight ribs, which are connected by
fifteen to twenty or more irregular, interrupted transverse bars. The
irregular quadrangular meshes so produced are filled up by an irregular
secondary network, with meshes of very different size and form. The dense
spongy envelope, which in the specimen figured covered only half the shell,
was complete in another older specimen.

_Dimensions._--Cephalis 0.015 long, 0.01 broad; thorax 0.4 long, 0.25
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Spongopyramis spongoplecta_, n. sp.

Shell entirely enveloped by spongy framework, pyramidal, with straight
outlines. Cephalis ovate (twice as large as in the preceding species), with
small circular pores. Thorax with twelve stout and straight ribs, which are
connected by twenty to twenty-five annular, transverse bars. The subregular
square meshes so produced are filled up by irregular, spongy network, which
envelops the whole shell more loosely than in _Spongopyramis spongiosa_.

_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax 0.5 long, 0.2 broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 563. _Acanthocorys_,[180] Haeckel, 1881, Prodromus, p. 432.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous radial ribs in the wall of the pyramidal thorax, prolonged into
divergent terminal feet. Network simple. Cephalis commonly with several
horns.

The genus _Acanthocorys_ and the following nearly allied _Arachnocorys_
possess a near relation to the three preceding pyramidal genera, but differ
from them in the terminal prolongation of the radial ribs, which are
commonly spiny and form a corona of free feet around the mouth of the
thorax. The cephalis is usually much larger than in the three preceding
genera, and bears a variable number of radial horns. Therefore these two
genera are probably older and nearer to the common ancestral form of the
Sethophormida than the preceding genera. It may be derived directly from
_Dictyophimus_ by interpolation of three secondary (interradial) ribs
between the three primary (perradial) ribs.



{1262}Subgenus 1. _Acanthocorallium_, Haeckel.

_Definition._--Thorax with six divergent ribs or radial beams (three
primary or perradial alternating with three secondary or interradial).


1. _Acanthocorys hexapodia_, n. sp.

Cephalis large, ovate, with subregular hexagonal pores, and six strong,
conical, simple, divergent horns of the same length. Thorax flat, conical,
smooth, with six large triangular basal holes, separated by six strong,
prismatic, smooth beams, which are connected only near the distal end by a
hexagonal ring of delicate, irregular network. Collar septum with three
meshes, separated by the three centripetal prolongations of the three
primary ribs.

_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.24
broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.


2. _Acanthocorys pristipodia_, n. sp.

Cephalis large, hemispherical, with irregular, polygonal pores, and
numerous (ten to twenty) bristle-shaped, radiating horns, which are conical
at the base, and twice as long. Thorax flatly campanulate, thorny, with six
strong, serrate or spinulate, divergent, radial ribs, prolonged into six
free conical feet of the same length. Meshes of the thorax irregular,
polygonal, a corona of six larger ones at the base. Collar septum with four
meshes, shaped as in Pl. 56, fig. 6.

_Dimensions._--Cephalis 0.04 long, 0.06 broad; thorax 0.08 long, 0.18
broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


3. _Acanthocorys macropodia_, n. sp.

Cephalis small, subspherical, with irregular, roundish pores and numerous
small, bristle-shaped horns. Length of the two joints = 1 : 2, breadth =
1 : 6. Thorax sexangular, pyramidal, with six very long and straight,
widely divergent feet, which are prismatic and spiny, and three to five
times as long as the breadth of the shell. Only the upper third of the six
ribs is connected by irregular, roundish network, with six large triangular
holes at the base. Collar septum with four meshes which have the same
relation to the six ribs as in _Sethophormis hexalactis_ (Pl. 56, fig. 6).

_Dimensions._--Cephalis 0.025 diameter, thorax 0.05 long, 0.15 broad.

_Habitat._--Central Pacific, Station 271, surface.


4. _Acanthocorys bütschlii_, Haeckel.

  ? _Clathrocanium ehrenbergii_, Bütschli, 1882, Zeitschr. f. wiss. Zool.,
  vol. xxxvi. pp. 514, 539, Taf. xxxii. fig. 18, _a_, _b_.

Cephalis large, subspherical, with numerous small, circular pores and three
to six divergent, slender, apical horns. Thorax flatly conical, smooth, not
much larger than the cephalis, with six {1263}large, triangular or ovate
basal holes between the six ribs. Three of these ribs are primary or
perradial, and arise immediately from the collar septum, alternating with
three secondary or interradial ribs, which arise more outside. The specimen
observed by me exhibited six apical horns, and was more complete than that
figured by Bütschli, the six ribs being prolonged over the connecting
lattice-girdle into six short, divergent feet.

_Dimensions._--Cephalis 0.06 long, 0.06 broad; thorax 0.08 long, 0.1 broad.

_Habitat._--Fossil in Barbados.



Subgenus 2. _Acanthocoronium_, Haeckel.

_Definition._--Thorax with nine divergent ribs or radial beams, three of
which are primary or perradial, the other six secondary or interradial.


5. _Acanthocorys umbellifera_, Haeckel.

  _Arachnocorys umbellifera_, Haeckel, 1862, Monogr. d. Radiol., p. 305,
  Taf. vi. fig. 12.

Cephalis large, ovate, with subregular, circular pores and numerous
divergent, simple spines of different lengths. Thorax flatly conical, with
nine strong, divergent ribs, which in the distal half are free, in the
proximal half connected by numerous transverse beams, forming irregular
polygonal meshes. Dorsal face of the thorax armed with scattered ascending
spines.

_Dimensions._--Cephalis 0.05 long, 0.035 broad; thorax 0.05 long, 0.12
broad.

_Habitat._--Mediterranean (Messina); Atlantic, Station 354, surface.


6. _Acanthocorys triloba_, n. sp.

Cephalis large, campanulate, trilobed, with irregular, roundish pores,
numerous spines, and a large pyramidal horn on the top, which is connected
by three constricted arches with the base of the horizontal collar beams.
From the latter arise as centrifugal prolongations three stout, curved,
primary ribs of the flatly vaulted thorax, and each of these gives off at
the base two opposite, lateral, secondary ribs. These nine ribs are spiny,
and connected by irregular, arachnoidal network.

_Dimensions._--Cephalis 0.05 long, 0.07 broad; thorax 0.08 long, 0.18
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


7. _Acanthocorys enneapodia_, n. sp.

Cephalis large, ovate, with irregular roundish pores, and numerous
divergent, ascending spines. Thorax smooth, conical, little larger, with
the same network, and nine larger, triangular holes at the base; with nine
straight, equally-disposed ribs, which are prolonged into slender feet
twice the length. With these latter alternate nine shorter radial spines,
arising from the truncate peristome.

_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.05 long, 0.09
broad.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.


{1264}8. _Acanthocorys macroceras_, n. sp. (Pl. 97, fig. 12).

Cephalis large, hemispherical, spiny, with regular, circular pores, and a
very large, cylindrical, vertical horn five times as long as the whole
shell. Thorax spiny, campanulate, with irregular, roundish pores and nine
strong, curved ribs, prolonged into nine slender, divergent feet twice the
length, which are curved, convex in the proximal half and concave in the
distal half.

_Dimensions._--Cephalis 0.05 long, 0.08 broad; thorax 0.12 long, 0.2 broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.


9. _Acanthocorys furcata_, n. sp.

Cephalis large, subspherical, spiny, with irregular, roundish pores. Thorax
flatly conical, thorny, with irregular, polygonal pores, decreasing in size
toward the mouth, and with nine straight divergent ribs, which at the
peristome are forked and prolonged into eighteen slender, very long,
bristle-shaped feet.

_Dimensions._--Cephalis 0.045 diameter, thorax 0.07 long, 0.13 broad.

_Habitat._--South Atlantic, Station 323, depth 1900 fathoms.



Subgenus 3. _Acanthocorythium_, Haeckel.

_Definition._--Thorax with a variable number (ten to twenty or more) radial
ribs, prolonged into free terminal feet.


10. _Acanthocorys dodecaster_, n. sp.

Cephalis small, subspherical, with small circular pores and a large conical
horn of twice the length, and some accessory spines. Thorax thorny, flatly
campanulate, with twelve stout curved ribs, which at the peristome are
prolonged into twelve slender, curved feet of twice the length; four of
them are centrifugal prolongations of the four cortinar beams separating
the four large meshes of the collar septum; eight other ribs are secondary,
interpolated in pairs between the former. At the base of the thorax are
twelve large triangular holes between the ribs; the other network is
irregular, with polygonal meshes.

_Dimensions._--Cephalis 0.03 diameter, thorax 0.05 long, 0.12 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


11. _Acanthocorys polypodia_, n. sp.

Cephalis small, hemispherical, with small, roundish pores and divergent
radial spines. Thorax flatly conical, spiny, with twenty to twenty-four
divergent, straight ribs, which in the proximal {1265}third are separated
by the same number of large, triangular meshes, in the middle third
connected by irregular network, in the distal third free.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.15
broad.

_Habitat._--Central Pacific, Station 273, depth 2350 fathoms.



Genus 564. _Arachnocorys_,[181] Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 837.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous radial ribs in the wall of the pyramidal thorax, prolonged into
divergent terminal feet. Network double, with an arachnoidal outer mantle
around the inner lattice-shell. Cephalis commonly with numerous horns.

The genus _Arachnocorys_ has been derived from the preceding
_Acanthocorys_, by development of numerous external siliceous threads which
connect the radial horns of the cephalis with the secondary spines arising
from the thoracic ribs. In this way there becomes formed an outer
arachnoidal framework, enveloping loosely, like a delicate mantle, the
inner primary lattice-shell.



Subgenus 1. _Arachnocorallium_, Haeckel.

_Definition._--Thorax with six divergent ribs or radial beams (three
primary or perradial, alternating with three secondary or interradial).


1. _Arachnocorys hexaptera_, n. sp.

  _Arachnocorys circumtexta_ (juv.?), R. Hertwig, 1879, Organism. d.
  Radiol., p. 79, Taf. viii. fig. 2_a_.

Cephalis large, subspherical, with irregular, polygonal pores, and numerous
bristle-shaped spines twice the length; on the centre of the top a single
larger vertical horn. Thorax flatly conical, with six strong and straight
widely divergent ribs, which in the proximal half are separated by six
large holes, in the distal half connected by a broad ring of irregular
network. From each rib arises a perpendicular branch, and these branches
are connected together, and with the spines of the cephalis, by arachnoidal
network.

_Dimensions._--Cephalis 0.04 diameter, thorax 0.08 long, 0.24 broad.

_Habitat._--Central Pacific, Station 266; Mediterranean, surface.


2. _Arachnocorys discoides_, n. sp.

Cephalis small, pyramidal, with irregular, roundish pores and numerous thin
spines, on the top a single larger vertical horn. Thorax very flat, nearly
discoidal, with six strong and straight ribs, {1266}which by communication
of few larger and numerous smaller branches form an irregular network with
polygonal meshes. From each of the six ribs arise two or three larger,
perpendicular branches of half the length, and from the network numerous
smaller spines. All these dorsal spines of the shell are connected by a
dense arachnoidal wicker-work.

_Dimensions._--Cephalis 0.02 diameter, thorax 0.04 long, 0.3 broad.

_Habitat._--Central Pacific, Station 271, surface.



Subgenus 2. _Arachnocoronium_, Haeckel.

_Definition._--Thorax with nine divergent ribs or radial beams, three of
which are primary or perradial, the other six secondary or interradial.
(Sometimes eight or ten occur instead of the nine normal ribs.)


3. _Arachnocorys circumtexta_, Haeckel.

  _Arachnocorys circumtexta_, Haeckel, 1862, Monogr. d. Radiol., p. 304,
  Taf. vi. figs. 9-11.

  _Arachnocorys circumtexta_, R. Hertwig, 1879, Organism. d. Radiol., p.
  78, Taf. viii. fig. 2.

Cephalis large, subspherical, with numerous roundish pores, and eight to
ten slender, conical horns twice the length. Thorax flatly conical, with
nine strong, straight, widely divergent, conical feet, each of which bears
in the middle of its outer side a perpendicular ascending branch of half
the length. These branches and the horns of the cephalis are connected by
very thin, parallel, arachnoidal threads. Network of the thorax irregular,
with nine larger triangular holes at the base. Collar septum with numerous,
irregular, roundish pores.

_Dimensions._--Cephalis 0.04 to 0.05 diameter, thorax 0.08 to 0.12 long,
0.15 to 0.25 broad.

_Habitat._--Mediterranean (Messina); Atlantic, Stations 347 to 354,
surface.


4. _Arachnocorys enneaptera_, n. sp.

Cephalis large, campanulate, with irregular, polygonal pores, two larger
stout pyramidal and numerous slender, bristle-shaped horns. Thorax of the
same structure as in the preceding species, only the nine basal holes are
of twice the size; the lower network denser (as in _Clathrocanium diadema_,
Pl. 64, fig. 2). Collar septum with numerous, irregular, roundish pores.

_Dimensions._--Cephalis 0.05 diameter, thorax 0.12 long, 0.22 broad.

_Habitat._--Tropical Atlantic, Station 338, surface.


5. _Arachnocorys araneosa_, n. sp. (Pl. 56, fig. 11).

Cephalis large, subspherical, with circular, subregular, hexagonally framed
pores, and twenty to thirty slender, cylindrical, straight radial spines.
Thorax flatly conical, nearly of the same shape as in the two preceding
species, but with nine longer ribs, and more irregular, broader network
between them. From the middle of each rib arises, nearly horizontally, a
strong branch, which is directed {1267}outwards. These branches are
connected with the spines of the cephalis as well as with the distal half
of the ribs, by dense and delicate arachnoidal network, composed of
parallel, very thin, siliceous threads (in fig. 11 only partially
represented).  Collar septum with numerous irregular, roundish pores.

_Dimensions._--Cephalis 0.04 diameter, thorax 0.1 long, 0.2 broad.

_Habitat._--Central Pacific, Station  270 to 274, surface.


6. _Arachnocorys arachnodiscus_, n. sp.

Cephalis small, campanulate, conical, with a single very large conical
central horn, and numerous smaller accessory spines. Thorax in form and
structure similar to that of the three preceding species, but much flatter,
being nearly discoidal. The meshes of the network are smaller and more
numerous, irregularly polygonal, and the nine basal holes little larger.
Collar septum with four large meshes (as in Pl. 60, fig. 6).

_Dimensions._--Cephalis 0.25 long, 0.3 broad; thorax 0.04 long, 0.24 broad.

_Habitat._--North Pacific, Station 248, surface.


7. _Arachnocorys trifida_, n. sp.

Cephalis large, campanulate, with irregular, roundish pores and numerous
ramified spines; in the centre of the top a larger pyramidal oblique horn
of twice the length. Thorax cap-shaped, flatly vaulted, with nine strong
convex ribs, prolonged into slender free feet. Three of these nine ribs are
the centrifugal prolongations of the three cortinar bars (united in the
centre of the collar stricture, separating its three large cortinar
meshes); the other six are diverging lateral branches of the former,
arising in pairs at both sides of its base. All nine ribs are connected by
delicate arachnoidal network with irregular polygonal meshes. From its
surface arise thin bristles, and from the base of each main rib a stout,
perpendicular branch. All these dorsal spines are connected by irregular,
arachnoidal wicker-work, covering thorax and cephalis. (A remarkable
primitive species?)

_Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.07 long, 0.18
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.



Subgenus 3. _Arachnocorythium_, Haeckel.

_Definition._--Thorax with a variable number of radial ribs (twelve to
twenty or more), prolonged into free terminal feet.


8. _Arachnocorys polyptera_, n. sp.

Cephalis large, subspherical, with irregular, roundish pores and numerous
radial spines. Thorax flatly conical, with numerous radial ribs (twenty to
thirty), which are in the distal half free, in the proximal half connected
by delicate arachnoidal wicker-work, with polygonal, irregular meshes. From
its dorsal face arise numerous radial spines, which are connected together,
and with the cephalic spines, by very thin and numerous threads, parallel
between every two spines. Similar to {1268}_Arachnocorys araneosa_ (Pl. 56,
fig. 11), but differing in the structure of the cephalis, and in the
greater number of the ribs and spines.

_Dimensions._--Cephalis 0.04 diameter, thorax 0.12 long, 0.24 broad.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.



Genus 565. _Anthocyrtoma_,[182] n. gen.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) without
thoracic ribs, with six terminal feet around the mouth. Cephalis free, with
an apical horn.

The genus _Anthocyrtoma_ and the four following genera form together the
peculiar group of Carpocanida, comprising all those Sethophormida in which
the original thoracic ribs are lost, and only the terminal feet remain.
_Anthocyrtoma_ is the simplest form of this group, possessing only six
terminal feet, three primary perradial, and three alternating, secondary,
interradial. It may be directly derived either from _Lychnocanium_, by
interpolation of three interradial feet, or from _Hexaspyris_ by loss of
the sagittal ring.


1. _Anthocyrtoma serrulata_, Haeckel.

  _Anthocyrtis serrulata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. vi. fig. 7.

Shell pear-shaped, rough, with obliterated collar stricture. Length of the
two joints = 1 : 4, breadth = 1 : 3. Cephalis ovate, with very small pores,
and a stout conical horn of the same length. Abdomen inflated, truncate,
with larger, regular, circular pores, twice as broad as the constricted
mouth. Six feet vertical, parallel, serrate, all of the same size, about as
long as the cephalis.

_Dimensions._--Cephalis 0.06 long, 0.05 broad; thorax 0.2 long, 0.17 broad.

_Habitat._--Fossil in Barbados.


2. _Anthocyrtoma alterna_, n. sp.

Shell pear-shaped, smooth, with distinct collar stricture. Length of the
two joints = 1 : 5, breadth = 1 : 6. Cephalis hemispherical, with a slender
conical horn of twice the length. Abdomen inflated, subglobular, with
regular, circular, hexagonally framed pores, three times as broad as the
narrow, constricted mouth. Six feet conical, smooth, somewhat divergent,
alternating, of different sizes; the three larger (perradial) half as long
as the shell, and twice as long as the three smaller (interradial).
(Similar to _Anthocyrtis ventricosa_.)

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.15 long, 0.18
broad.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.



{1269}Genus 566. _Anthocyrtis_,[183] Ehrenberg, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, 1847, p. 54.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) without
thoracic ribs, with nine terminal feet around the mouth. Cephalis free,
with an apical horn.

The genus _Anthocyrtis_ (in the original definition of Ehrenberg) contained
all Dicyrtida without thoracic ribs, with terminal feet. We here restrict
the definition to those Sethophormida in which the number of free terminal
feet is constantly nine (three primary perradial and three alternate pairs
of secondary interradial feet). _Anthocyrtis_ may be derived either
directly from _Patagospyris_ by loss of the sagittal ring, or from
_Lychnocanium_ by interpolation of three secondary feet.



Subgenus 1. _Anthocyrtella_, Haeckel.

_Definition._--Feet of the peristome-corona divergent, their basal distance
less than their terminal distance.


1. _Anthocyrtis mespilus_, Ehrenberg.

  _Anthocyrtis mespilus_, Ehrenberg, 1854, Taf. xxxvi. fig. 13; Abhandl. d.
  k. Akad. d. Wiss. Berlin, 1875, p. 66, Taf. vi. fig. 4 (not 5).

Shell smooth, with distinct collar stricture. Length of the two joints =
1 : 5, breadth = 2 : 6. Cephalis hemispherical, with a stout pyramidal horn
of twice the length. Thorax nearly hemispherical, with regular, circular,
quincuncial pores. Mouth scarcely constricted, with nine divergent,
triangular, lamellar feet, about as long as the thorax.

_Dimensions._--Cephalis 0.012 long, 0.02 broad; thorax 0.05 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


2. _Anthocyrtis furcata_, Ehrenberg.

  _Anthocyrtis furcata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 64, Taf. vi. fig. 2.

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 5,
breadth = 2 : 6. Cephalis hemispherical, with a short pyramidal horn of
half the length. Thorax hemispherical, with large, irregular, roundish
pores. Mouth scarcely constricted, with nine divergent, curved, slender
feet, which are about as long as the shell, and forked at the distal end.

_Dimensions._--Cephalis 0.01 long, 0.02 broad; thorax 0.05 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


{1270}3. _Anthocyrtis butomus_, n. sp.

Shell thorny, with obliterated collar stricture. Length of the two joints =
2 : 6, breadth = 2 : 7. Cephalis ovate, with very small and scarce pores,
and a conical horn of the same length. Thorax inflated, pear-shaped, with
regular, circular, quincuncial pores. Mouth about half as broad,
constricted, with nine divergent, broad, nearly square, lamellar feet, half
as long as the thorax (similar to _Anthocyrtis serrulata_, Ehrenberg, _loc.
cit._, Taf. vi. fig. 7).

_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.14
broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


4. _Anthocyrtis ventricosa_, Ehrenberg.

  _Anthocyrtis ventricosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. viii. fig. 1.

Shell thorny, with obliterated collar stricture. Length of the two joints =
1 : 7, breadth = 2 : 7. Cephalis hemispherical, hyaline, without pores,
with a slender, conical horn, of about the same length. Thorax inflated,
pear-shaped or subspherical, with regular, circular, quincuncial pores.
Mouth only one-third as broad, much constricted, with nine divergent,
slender, conical feet, about one-fifth as long as the diameter of the shell
(partly broken off in Ehrenberg's figure).

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.14 long, 0.14
broad.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms; also fossil
in Barbados.



Subgenus 2. _Anthocyrtissa_, Haeckel.

_Definition._--Feet of the peristome-corona parallel, vertical; their basal
and terminal distances equal.


5. _Anthocyrtis ophirensis_, Ehrenberg.

  _Anthocyrtis ophirensis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 285, Taf. ix. fig. 13.

Shell smooth, with slight collar stricture. Length of the two joints =
2 : 4, breadth = 1 : 5. Cephalis ovate, with irregular, roundish pores, and
a pyramidal, excentric, vertical horn of the same length. Thorax
campanulate, with delicate network of large, regular, hexagonal pores.
Mouth scarcely constricted, with nine parallel, vertical, conical feet,
about as long as the cephalis. (In the specimen figured by Ehrenberg only
seven feet are represented, two being broken off; two other specimens of
this species, captured by Rabbe, exhibited nine regularly disposed feet.)

_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax 0.08 long, 0.1 broad.

_Habitat._--Indian Ocean, Zanzibar (Pullen); Madagascar (Rabbe), surface.


{1271}6. _Anthocyrtis lauranthus_, n. sp.

Shell smooth with slight collar stricture. Length of the two joints =
1 : 3, breadth = 1 : 4. Cephalis ovate, with large, roundish pores, and a
conical horn of twice the length. Thorax inflated, campanulate, with
regular, circular, hexagonally framed pores. Mouth two-thirds as broad,
little constricted, with nine parallel, vertical, broad, lamellar,
triangular feet, half as long as the cephalis.

_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax 0.1 long, 0.12 broad.

_Habitat._--Central Pacific, Station 266 to 270, depth 2550 to 2925
fathoms.


7. _Anthocyrtis grossularia_, Ehrenberg.

  _Anthocyrtis grossularia_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 64, Taf. vi. fig. 6.

Shell spiny, with deep collar stricture. Length of the two joints = 1 : 5,
breadth = 1 : 4. Cephalis subspherical, thorny, with a conical horn of the
same length. Thorax ovate, spiny, with numerous densely-crowded,
subregular, circular pores. Mouth about half as broad, constricted, with
nine parallel, vertical, slender, conical feet, about as long as the
cephalis.

_Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.2 long, 0.18 broad.

_Habitat._--Fossil in Barbados.


8. _Anthocyrtis subglobosa_, n. sp.

Shell spiny, with deep collar stricture. Length of the two joints = 1 : 7,
breadth = 1 : 7. Cephalis subspherical, with a conical horn twice the
length. Thorax nearly spherical, with small and very numerous, regular,
circular pores. Mouth only one-third as broad, constricted, with nine
parallel, vertical, square, lamellar feet, about twice as long as the
cephalis.

_Dimensions._--Cephalis 0.03 long, 0.035 broad; thorax 0.2 long, 0.2 broad.

_Habitat._--South Pacific, Station 297, depth 1775 fathoms.



Subgenus 3. _Anthocyrtura_, Haeckel.

_Definition._--Feet of the peristome-corona convergent, their basal
distance greater than their terminal distance.


9. _Anthocyrtis enneaphylla_, n. sp.

Shell smooth, with sharp collar stricture. Length of the two joints =
1 : 6, breadth = 1 : 5. Cephalis subspherical, with a conical horn twice
the length, nearly hyaline, with very small and scarce pores. Thorax nearly
spherical, with regular, circular, quincuncial pores. Mouth only {1272}half
as broad, with nine broad, triangular feet, twice as long as the cephalis,
and curved inwards, convergent towards the main axis.

_Dimensions._--Cephalis 0.02 long, 0.025 broad; thorax 0.11 long, 0.12
broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


10. _Anthocyrtis ovata_, n. sp. (Pl. 62, fig. 13).

Shell smooth, with slight collar stricture. Length of the two joints =
1 : 5, breadth = 1 : 3. Cephalis ovate, with numerous small pores, and an
excentric conical horn of the same length. Thorax ovate, with regular,
circular, quincuncial pores. Mouth nearly of the same breadth, scarcely
constricted, with nine triangular, widely-separated feet, about as long as
the cephalis, and convergent towards the main axis.

_Dimensions._--Cephalis 0.035 long, 0.03 broad; thorax 0.15 long, 0.1
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Genus 567. _Anthocyrtium_,[184] n. gen.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) without
thoracic ribs, with numerous terminal feet around the mouth (twelve to
fifteen or more). Cephalis free, with an apical horn.

The genus _Anthocyrtium_ has been derived from the two preceding genera by
further multiplication of the terminal feet, the number of which is at
least twelve to fifteen, often twenty or more. It may be that some species
have arisen directly from _Patagospyris_ by loss of the sagittal ring.



Subgenus 1. _Anthocyrtarium_, Haeckel.

_Definition._--Feet of the peristome-corona divergent, their basal distance
less than their terminal distance.


1. _Anthocyrtium chrysanthemum_, n. sp. (Pl. 62, fig. 14).

Shell smooth, with distinct collar stricture. Length of the two joints =
3 : 7, breadth = 4 : 9. Cephalis hemispherical, with small, circular pores,
and a large, straight, cylindro-conical horn, about as long as the shell.
Thorax campanulate, hemispherical, with six to eight transverse rows of
squarish pores, increasing in size downwards. Mouth little constricted,
with twelve to fifteen divergent, curved, slender feet, about as long as
the thorax.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.07 long, 0.09
broad.

_Habitat._--Central Pacific, Station 270 to 274, depth 2350 to 2925
fathoms.


{1273}2. _Anthocyrtium centaurea_, Haeckel.

  _Anthocyrtis mespilus_, var. _major_, Ehrenberg, 1875, Abhandl. d. k.
  Akad. d. Wiss. Berlin, p. 66, Taf. vi. fig. 5.

Shell smooth, with sharp collar stricture. Length of the two joints =
2 : 6, breadth = 3 : 7. Cephalis hemispherical, with irregular, roundish
pores, and a very large pyramidal horn, longer than the shell, with
contorted edges. Thorax hemispherical, with six to eight transverse rows of
regular, circular pores of equal size. Mouth little constricted, with
fifteen to twenty divergent, curved, slender feet, about as long as the
shell.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.07
broad.

_Habitat._--Fossil in Barbados.


3. _Anthocyrtium anthemis_, n. sp.

Shell papillate, with obliterated collar stricture.  Length of the two
joints = 1 : 3, breadth = 1 : 3. Cephalis hemispherical, with very small
and scarce pores, and a conical horn of the same length. Thorax conical, as
long as broad, with conical papillæ, and eight to ten transverse rows of
roundish pores, gradually increasing in size downwards. Mouth scarcely
constricted, with fifteen to twenty divergent, straight, conical feet, half
as long as the thorax.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.09
broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


4. _Anthocyrtium collare_, Haeckel.

  _Anthocyrtis collaris_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 64, Taf. vi. fig. 8.

Shell rough, conical, with obliterated collar stricture. Length of the two
joints = 3 : 5, breadth = 4 : 7. Cephalis conical, with a pyramidal horn of
the same length, and with two transverse rows of rather oblong, narrow
pores. Thorax truncate, conical, in the lower part thorny, with six to
eight transverse rows of regular, circular pores, increasing in size
downwards.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.05 long, 0.07
broad.

_Habitat._--Fossil in Barbados.


5. _Anthocyrtium adonis_, n. sp. (Pl. 62 fig. 20).

Shell rough, with sharp collar stricture. Length of the two joints =
3 : 10, breadth = 4 : 12. Cephalis subspherical, with very small circular
pores, and a very long, straight cylindrical, horn, twice to three times as
long as the shell. Thorax inflated, ovate, or subspherical, with small
regular, circular, hexagonally-framed pores. Mouth strongly constricted,
half as broad as the thorax, with fifteen to {1274}twenty divergent, broad,
lamellar, rectangular feet, as long as the thorax, and so densely placed
that their margins come in contact with one another.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.12 broad.

_Habitat._--Central Pacific, Station 263 to 268, depth 2650 to 3000
fathoms.


6. _Anthocyrtium anemone_, n. sp.

Shell spiny, with sharp collar stricture. Length of the two joints = 1 : 5,
breadth = 1 : 4. Cephalis subspherical, with a conical horn of half the
length, hyaline, without pores. Thorax spiny, pear-shaped, inflated, with
small and numerous, regular, circular pores. Mouth constricted, half as
broad as the thorax, with twelve to fifteen divergent, slender, conical,
denticulate feet, half as long as the thorax.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.14 long, 0.12
broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms; also fossil
in Barbados.



Subgenus 2. _Anthocyrtonium_, Haeckel.

_Definition._--Feet of the peristome-corona parallel, vertical; their basal
and apical distances equal.


7. _Anthocyrtium campanula_, n. sp. (Pl. 62, fig. 17).

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 3,
breadth = 1 : 3. Cephalis spherical, with a conical horn of the same
length. Thorax campanulate, thin-walled, with delicate network of regular,
hexagonal pores and thin bars. Mouth little constricted, with twenty to
twenty-four parallel, vertical, lanceolate feet, about as long as the
cephalis.

_Dimensions._--Cephalis 0.03 diameter, thorax 0.09 long, 0.1 broad.

_Habitat._--South Pacific, Station 302, depth 1450 fathoms.


8. _Anthocyrtium reticulatum_, Haeckel.

  _Thyrsocyrtis reticulata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 84, Taf. xii. fig. 10.

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 2,
breadth = 1 : 3. Cephalis hemispherical, with a prismatic, denticulate horn
of the same length, and small, irregular pores. Thorax campanulate, thorny,
thin-walled, with delicate network of irregular, polygonal pores. Mouth
little constricted, with twelve (or more) small, parallel, vertical,
triangular feet, shorter than the cephalis.

_Dimensions._--Cephalis 0.015 long, 0.02 broad; thorax 0.04 long, 0.06
broad.

_Habitat._--Fossil in Barbados.


{1275}9. _Anthocyrtium leptostylum_, Haeckel.

  _Anthocyrtis leptostyla_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 64, Taf. vi. fig. 1.

Shell thorny, with slight collar stricture. Length of the two joints =
1 : 5, breadth = 2 : 4. Cephalis hemispherical, with small, scarce pores
and a slender conical horn of the same length. Thorax spiny, with regular,
circular, quincuncial pores. Mouth constricted, half as broad, with twelve
to eighteen slender, parallel, vertical feet, about as long as the
cephalis.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.1 long, 0.08 broad.

_Habitat._--Central Pacific, Stations 266 to 270, depth 2550 to 2925
fathoms; also fossil in Barbados.


10. _Anthocyrtium hispidum_, Haeckel.

  _Anthocyrtis hispida_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 64, Taf. viii. fig. 2.

  _Anthocyrtis hispida_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
  xxxvi. p. 540, Taf. xxxiii. fig. 30.

Shell thorny, with sharp collar stricture. Length of the two joints =
1 : 4, breadth = 2 : 5. Cephalis hemispherical, hyaline, with few very
small pores, or without any; with a stout conical horn of twice the length.
Thorax spiny, with regular, circular, hexagonally-framed pores (half as
broad as the bars between them). Mouth wide open, scarcely constricted,
with twelve to fifteen parallel, vertical, broad, lamellar, rectangular
feet, reaching nearly the length of the thorax.

_Dimensions._--Cephalis 0.02 to 0.03 long, 0.03 to 0.05 broad; thorax 0.07
to 0.09 long, 0.1 to 0.12 broad.

_Habitat._--Central Pacific, Stations 263 to 265, depth 2650 to 3000
fathoms; also fossil in Barbados.


11. _Anthocyrtium turris_, n. sp.

Shell thorny, very similar to _Calocyclas turris_, Ehrenberg (1875, _loc.
cit._, Taf. xviii. fig. 7), but without fenestrated abdomen. Collar
stricture deep. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis
subspherical, hyaline, without pores, with a stout conical horn of twice
the length. Thorax nearly spherical, spiny, with regular, circular,
quincuncial pores. Mouth little constricted, with fifteen to twenty
parallel, vertical, broad, lamellar, rectangular feet, about as long as the
thorax.

_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.1 broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


{1276}12. _Anthocyrtium doronicum_, n. sp. (Pl. 62, fig. 18).

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 5,
breadth = 1 : 3. Cephalis hemispherical, with small, circular pores and a
stout conical horn of twice the length. Thorax campanulate, subcylindrical,
with regular, circular, quincuncial pores, three to four times as broad as
the bars. Mouth scarcely constricted, with twenty-four to thirty vertical,
nearly parallel, little curved feet, which are about half as long as the
shell, broad, lamellar, rectangular, and in close contact with their edges.

_Dimensions._--Cephalis 0.025 long, 0.035 broad, thorax 0.12 long, 0.1
broad.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.



Subgenus 3. _Anthocyrturium_, Haeckel.

_Definition._--Feet of the peristome-corona convergent, their basal
distance greater than their apical distance.


13. _Anthocyrtium pyrum_, n. sp. (Pl. 62, fig. 12).

Shell smooth, with obliterated collar stricture. Length of the two joints =
2 : 7, breadth = 3 : 8. Cephalis hemispherical, with a small,
bristle-shaped horn of half the length. Thorax inflated, subglobose, with
regular, circular, quincuncial pores and thin bars. Mouth constricted, only
half as broad, with fifteen to twenty small, triangular, convergent feet,
shorter than the cephalis. (In another specimen the feet were twice as
long, stronger and more convergent, than in the one figured.)

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.8 broad.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.


14. _Anthocyrtium setosum_, Haeckel.

  _Anthocyrtis setosa_, Haeckel, 1862, Monogr. d. Radiol., p. 311.

  ? _Lithopera setosa_, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B., B. iv.
  fig. 23.

Shell spiny, with sharp collar stricture. Length of the two joints = 1 : 2,
breadth = 1 : 3. Cephalis hemispherical, with a conical horn of the same
length and some accessory spines. Thorax campanulate, with subregular,
circular pores. Mouth little constricted, with twenty to thirty small,
triangular, convergent feet, about as long as the cephalis. (In Ehrenberg's
incomplete figure they are mostly broken off.)

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.04 long, 0.06
broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.


{1277}15. _Anthocyrtium ehrenbergii_, Haeckel.

  _Anthocyrtis ehrenbergii_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 100,
  Taf. iii. fig. 21, _a_, _b._

Shell smooth, with obliterated collar stricture. Length of the two joints =
3 : 10, breadth = 2 : 8. Cephalis subcylindrical, with an excentric, stout,
pyramidal horn of the same length. Thorax bottle-shaped, with small,
regular, circular pores of equal size. Mouth little constricted, with
twenty to thirty small, triangular, convergent feet, about half as long as
the cephalis.

_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax 0.1 long, 0.08 broad.

_Habitat._--Fossil in Tertiary rocks of Sicily (Grotte), Stöhr.


16. _Anthocyrtium zanguebaricum_, Haeckel.

  _Anthocyrtis zanguebarica_, Ehrenberg, 1872, Abhandl. d. k. Akad. d.
  Wiss. Berlin, p. 285, Taf. ix. fig. 12.

Shell smooth, with slight collar stricture. Length of the two joints =
3 : 10, breadth = 2 : 7. Cephalis subspherical, with an excentric conical
horn of the same length. Thorax slender, ovate or bottle-shaped, with
irregular, roundish pores increasing in size downwards. Mouth little
constricted, with twelve to fifteen small, triangular, convergent feet,
about half as long as the cephalis.

_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax 0.1 long, 0.07 broad.

_Habitat._--Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.


17. _Anthocyrtium ficus_, Haeckel.

  _Anthocyrtis ficus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 64, Taf. vi. fig. 3.

Shell rough, with obliterated collar stricture. Length of the two joints =
2 : 12, breadth = 3 : 10. Cephalis conical, with a large, cylindrical horn,
pyramidal at the base, about as long as the thorax. Thorax subovate,
truncate, papillate, with small, regular, circular, quincuncial pores of
the same breadth as the bars. Mouth constricted, two-thirds as broad as the
thorax, with fifteen to twenty strongly convergent, lamellar, rectangular
or sword-shaped feet, nearly as long as the thorax.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.12 long, 0.1 broad.

_Habitat._--Fossil in Barbados.


18. _Anthocyrtium flosculus_, n. sp. (Pl. 62, fig. 19).

  _Anthocyrtis flosculus_, Haeckel, 1881, Prodromus et Atlas, pl. lxii.
  fig. 19.

Shell ribbed, with distinct collar stricture. Length of the two joints =
1 : 4, breadth = 2 : 4. Cephalis hemispherical, with small, circular pores
and a large cylindrical horn, twice as long as the thorax and half as broad
at the base as the cephalis. Thorax subovate, truncate, with twenty-four to
thirty longitudinal ribs and alternating rows of circular pores. Mouth
constricted, two-thirds {1278}as broad as the thorax, with twenty-four to
thirty slender, convergent feet, which are as long as the entire shell,
with their edges in close contact and their distal ends pointed.

_Dimensions._--Cephalis 0.03 long, 0.05 broad; thorax 0.12 long, 0.12
broad.

_Habitat._--Central Pacific, Stations 265 to 274, depth 2350 to 2925
fathoms.



Genus 568. _Anthocyrtidium_,[185] Haeckel, 1881, Prodromus, p. 431.

_Definition._--#Sethophormida#, (vel Dicyrtida multiradiata aperta) without
thoracic ribs, with numerous (twelve to fifteen or more) subterminal feet,
which are separated from the constricted mouth by a ring of lattice-work.
Cephalis free, with an apical horn.

The genus _Anthocyrtidium_ has been derived from the preceding
_Anthocyrtium_ by further growth and constriction of the peristome, which
becomes separated from the subterminal corona of feet by a more or less
broad ring of lattice-work.


1. _Anthocyrtidium cineraria_, n. sp. (Pl. 62, fig. 16).

Shell campanulate, smooth, with obliterated collar stricture. Length of the
two joints = 5 : 11, breadth = 3 : 13. Cephalis subcylindrical-ovate, with
a conical straight horn of half the length. Thorax hemispherical, inflated,
nearly twice as broad as the constricted mouth. Pores subregular, circular,
double-contoured. Above the mouth, separated from it by two rows of pores,
a corona of twelve to fifteen short conical feet, which are directed
downwards, slightly curved, and as long as the cephalic horn.

_Dimensions._--Cephalis 0.05 long, 0.03 broad; thorax 0.11 long, 0.13
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


2. _Anthocyrtidium ligularia_, n. sp. (Pl. 62, fig. 15).

Shell campanulate, rough, with distinct collar stricture. Length of the two
joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical, with a slender,
conical, slightly curved horn, about as long as the shell. Thorax
hemispherical, three times as broad as the cephalis, nearly twice as broad
as the constricted mouth, which is prolonged into a prominent smooth ring.
Above the mouth, separated from it by one row of pores, a corona of twelve
to fifteen slender linear feet, which are slightly curved, divergent, and
emarginate at the truncated distal end.

_Dimensions._--Cephalis 0.015 long, 0.03 broad; thorax 0.06 long, 0.09
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


{1279}3. _Anthocyrtidium matricaria_, n. sp.

Shell campanulate, rough, very similar to the preceding species, but
differing in the straight, large, pyramidal horn of the cephalis (as long
as the shell), and in the longer feet, which are twelve to fifteen in
number, little curved at the distal end, pointed, and about as long as the
shell. Length of the two joints = 2 : 6, breadth = 3 : 8. Differs from the
similar _Anthocyrtium centaurea_, Ehrenberg (1875, _loc. cit._, Taf. vi.
fig. 5), mainly in the prominent ring of the peristome.

_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08
broad.

_Habitat._--Fossil in Barbados.



Genus 569. _Carpocanium_,[186] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.

_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) without
thoracic ribs, with numerous terminal feet around the mouth (six to twelve
or more). Cephalis hidden in the thorax, without apical horn.

The genus _Carpocanium_, very common, and rich in numerous living and
fossil species, was formerly placed by me among the true Monocyrtida, since
an external constriction is not visible (Monogr., 1862, p. 290). Afterwards
(in 1879) Richard Hertwig demonstrated that the cavity of the ovate shell,
externally simple, is divided by an internal transverse septum into two
joints, the upper of which is the flat rudimentary cephalis (Organism. d.
Radiol., p. 79; compare also Bütschli, 1882, _loc. cit._, p. 535). Indeed
this septum, with four central crossed cortinar beams, is a true collar
septum, and _Carpocanium_ has been derived from _Anthocyrtis_ or
_Desmospyris_ by reduction of the cephalis, which is very flat and
perfectly hidden in the uppermost part of the thorax. The apical horn is
lost. If the internal septum were to become lost, the genus would pass over
into _Carpocanistrum_.



Subgenus 1. _Carpocanarium_, Haeckel.

_Definition._--Peristome-corona composed of six feet (three primary
perradial alternating with three secondary interradial).


1. _Carpocanium calycodes_, Stöhr.

  _Carpocanium calycodes_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf.
  iii. fig. 8.

Shell urceolate, smooth, nearly twice as long as broad, with hemispherical
vaulted cephalis. Length of the two joints = 3 : 16, breadth = 5 : 10.
Pores regular, circular, as broad as the bars, {1280}quincuncially disposed
in about five longitudinal series at each side. Mouth constricted, half as
broad as the thorax. Peristome with six vertical, equilateral, triangular
feet.

_Dimensions._--Cephalis 0.015 long, 0.025 broad; thorax 0.08 long, 0.05
broad.

_Habitat._--Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).


2. _Carpocanium setosum_, Haeckel.

  _Halicalyptra setosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 160, Taf. ii. fig. 12.

Shell ovate, truncate at the mouth, thorny, exactly as long as broad.
Length of the two joints = 1 : 8, breadth = 3 : 9. Cephalis hidden, with
very small pores. Thorax inflated, with regular, circular pores, twice as
broad as the bars, in about ten longitudinal series at each side. Mouth
constricted, half as broad as the thorax. Peristome with six vertical,
parallel, broad, lamellar, rectangular feet, separated by equal internals,
half as long as the shell.

_Dimensions._--Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.09
broad.

_Habitat._--Fossil in Barbados.


3. _Carpocanium laeve_, Ehrenberg.

  _Carpocanium laeve_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287.

Shell subspherical, smooth, equal in length and breadth, with little
vaulted, cap-shaped cephalis. Length of the two joints = 1 : 6, breadth =
4 : 7. Pores regular, circular, twice as broad as the bars, in nine
longitudinal rows. Mouth constricted, only one-third as broad as the
thorax. Peristome with six strong conical feet, which are slightly curved
and convergent.

_Dimensions._--Cephalis 0.01 long, 0.04 broad; thorax 0.06 long, 0.07
broad.

_Habitat._--Mediterranean (Greece); Tropical Atlantic, Station 348, depth
2450 fathoms.


4. _Carpocanium lanceolatum_, n. sp.

Shell subspherical, thorny, with perfectly hidden cephalis. Length of the
two joints = 1 : 3, breadth = 1 : 3. Pores regular, circular, hexagonally
framed, half as broad as the bars, in about sixteen longitudinal rows at
each side. Mouth constricted, half as broad as the thorax. Peristome with
six large lanceolate, vertical, lamellar feet, half as long as the shell.

_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.09 long, 0.09
broad.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.



Subgenus 2. _Carpocanidium_, Haeckel.

_Definition._--Peristome-corona composed of nine feet (three primary
perradial and six secondary interradial).


{1281}5. _Carpocanium diadema_, Haeckel.

  _Carpocanium diadema_, Haeckel, 1862, Monogr. d. Radiol., p. 290, Taf. v.
  fig. 1.

  _Carpocanium diadema_, R. Hertwig, 1879, Organism. d. Radiol., p. 79,
  Taf. viii. figs. 7, 7_a_, 8, 8_a_, 8_b_.

Shell ovate, with little vaulted cephalis. Length of the two joints =
1 : 8, breadth = 3 : 6. Pores regular, circular, in about twelve
longitudinal rows, twice as broad as the bars. Mouth constricted, half as
broad as the thorax. Peristome with nine vertical, equilateral, triangular
feet.

_Dimensions._--Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.06
broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; many
stations, surface.


6. _Carpocanium cylindricum_, n. sp.

Shell cylindrical, with hemispherical, flatly vaulted cephalis. Length of
the two joints = 1 : 4, breadth = 3 : 3. Pores regular, circular,
double-contoured, as broad as the bars, in about fifteen longitudinal
series. Mouth constricted, two-thirds as broad as the thorax. Peristome
with nine vertical, slender, triangular, pointed feet.

_Dimensions._--Cephalis 0.02 long, 0.06 broad; thorax 0.08 long, 0.06
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


7. _Carpocanium enneaphyllum_, n. sp.

Shell slenderly ovate, at the mouth truncate, thorny, with hemispherical,
vaulted cephalis. Length of the two joints = 1 : 6, breadth = 2 : 4. Pores
regular, circular, hexagonally framed, as broad as the bars, in about
thirteen longitudinal rows. Mouth constricted, about two-thirds as broad as
the thorax. Peristome with nine broad, lamellar, vertical, nearly square
feet, half as long as the shell, with small intervals.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.09
broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.


8. _Carpocanium solitarium_, Ehrenberg.

  _Carpocanium solarium_, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 28.

  _Lithocampe solitaria_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad.
  d. Wiss. Berlin, p. 65.

Shell slenderly ovate, twice as long as broad, with hidden spherical
cephalis, completely enclosed in the summit of the thorax. Length of the
two joints = 1 : 6, breadth = 1 : 4. Pores small, regular, circular, as
broad as the bars, in about eleven longitudinal rows. Mouth gradually
constricted, half as broad as the thorax. Peristome with nine ovate blunt
feet, which are as long as the cephalis, little curved and convergent.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.12 long, 0.07
broad.

_Habitat._--Fossil in Tertiary rocks of Sicily (Caltanisetta).


{1282}9. _Carpocanium gemmula_, n. sp.

Shell subspherical, smooth, equal in length and breadth, with hemispherical
vaulted cephalis. Length of the two joints = 2 : 7, breadth = 4 : 9. Pores
small, regular, circular, twice as broad as the bars, in about twenty
longitudinal rows. Mouth strongly constricted, only one-fourth as broad as
the thorax. Peristome with nine conical feet, which are twice as long as
the cephalis, curved, and so convergent that their distal ends come nearly
in contact.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.07 long, 0.09
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.


10. _Carpocanium microdon_, Ehrenberg.

  _Carpocanium microdon_, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad.
  d. Wiss. Berlin, p. 30.

Shell broad, ovate, rough, with perfectly hidden cephalis. Length of the
two joints = 2 : 9, breadth = 4 : 7. Pores very small and scarce, smaller
than the bars between them, irregularly scattered. Mouth constricted,
one-third as broad as the thorax. Peristome with nine short, triangular,
pointed, convergent feet.

_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.07
broad.

_Habitat._--Mediterranean (Crete), Atlantic (Canary Islands), Station 354,
surface.



Subgenus 3. _Carpocanobium_, Haeckel.

_Definition._--Peristome-corona composed of twelve or more feet.


11. _Carpocanium trepanium_, n. sp. (Pl. 52, fig. 18).

Shell subcylindrical, with flatly vaulted cephalis. Length of the two
joints = 1 : 6, breadth = 3 : 4. Pores regular, hexagonal, four to six
times as broad as the bars. Mouth little constricted, two-thirds as broad
as the thorax. Peristome with eighteen to twenty-four large, slender,
triangular, vertical feet.

_Dimensions._--Cephalis 0.02 long, 0.06 broad; thorax 0.12 long, 0.08
broad.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.


12. _Carpocanium hexagonale_, n. sp. (Pl. 52, fig. 15).

Shell broadly ovate or subconical, with vaulted, cap-shaped cephalis.
Length of the two joints = 2 : 7, breadth = 6 : 9. Thorax subglobular,
truncate. Pores subregular, hexagonal, three to four times as broad as the
bars. Mouth constricted, two-thirds as broad as the thorax. Peristome with
twenty to twenty-five small, triangular, vertical feet.

_Dimensions._--Cephalis 0.02 long, 0.05 broad; thorax 0.07 long, 0.09
broad.

_Habitat._--Tropical Atlantic, Station 347, surface.


{1283}13. _Carpocanium petalospyris_, n. sp. (Pl. 52, fig. 19).

Shell subspherical, smooth, with perfectly hidden cephalis. Length of the
two joints = 1 : 6, breadth = 3 : 6. Pores regular, circular,  hexagonally
framed, twice as broad as the bars, in about sixteen longitudinal rows.
Mouth slightly constricted, little narrower than the thorax. Peristome with
twenty to twenty-four vertical, broad, lamellar feet, which are nearly as
long as the shell, at the distal end truncate, and almost in contact at
their edges.

_Dimensions_.--Cephalis 0.02 long, 0.05 broad; thorax 0.11 long, 0.12
broad.

_Habitat_.--Central Pacific, Station 271, depth 2425 fathoms.


14. _Carpocanium polypterum_, Haeckel.

  _Cryptoprora polyptera_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 287, Taf. ix. fig. 17.

  _Carpocanium macropterum_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 302.

Shell campanulate-conical, smooth, with perfectly hidden cephalis. Length
of the two joints = 1 : 6, breadth = 4 : 6. Pores regular, circular, twice
as broad as the bars, in about sixteen longitudinal rows. Mouth wide open,
not constricted. Peristome with twenty to thirty vertical, slender, conical
feet, about as long as the shell.

_Dimensions_.--Cephalis 0.01 long, 0.04 broad; thorax 0.06 long, 0.06
broad.

_Habitat_.--Indian Ocean (Zanzibar), depth 2200 fathoms (Pullen).


15. _Carpocanium palmipes_, n. sp.

Shell ovate, very thick-walled, smooth. Lower half of the subspherical
cephalis hidden in the summit of the thorax, upper half free, with few
small pores. Length of the two joints = 3 : 10, breadth = 3 : 10. Thorax
foveolate, with oblong dimples, each of which encloses a small, circular,
double-contoured pore, half as broad as the bars. Mouth little constricted,
nearly as broad as the thorax. Peristome prolonged into a solid,
cylindrical tube, nearly as long and as broad as the shell; the upper half
of the tube is solid, the lower divided into from twelve to fifteen
vertical, lamellar, pointed feet.

_Dimensions_.--Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.1 broad.

_Habitat_.--Western Tropical Pacific, Station 225, depth 4475 fathoms.


16. _Carpocanium peristomium_, n. sp. (Pl. 52, figs. 16, 17).

Shell ovate, smooth, with perfectly hidden, flat cephalis (fig. 17). Length
of the two joints = 2 : 10, breadth = 5 : 9. Pores small and very numerous,
regular, circular, as broad as the bars, in about twenty longitudinal rows.
Mouth little constricted. Peristome broad; in the upper {1284}half a
hyaline, circular ring, in the lower half divided into from eighteen to
twenty-four triangular, curved, little convergent feet.

_Dimensions._--Cephalis 0.02 long, 0.05 broad; thorax 0.1 long, 0.09 broad.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific; many stations, at
various depths.


17. _Carpocanium coronatum_, Ehrenberg.

  _Carpocanium coronatum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 66, Taf. v. fig. 7.

Shell ovate, smooth, with perfectly hidden, subspherical cephalis. Length
of the two joints = 2 : 9, breadth = 2 : 8. Pores small and very numerous,
twice as broad as the bars, regular, circular, in about twenty longitudinal
rows. Mouth little constricted, two-thirds as broad as the thorax.
Peristome with twenty-five to thirty short, bristle-shaped feet, which are
slightly curved, convergent, and in the upper half connected by a solid
ring.

_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.08
broad.

_Habitat._--Fossil in Barbados.


18. _Carpocanium dactylus_, n. sp.

Shell slenderly ovate, twice as long as broad, with flat, perfectly hidden
cephalis. Length of the two joints = 1 : 12, breadth = 4 : 8. Pores
subregular, circular, as broad as the bars, in about twelve longitudinal
rows, separated by prominent longitudinal ribs. Mouth constricted,
two-thirds as broad as the thorax. Peristome with twelve large, lanceolate,
lamellar, convergent feet.

_Dimensions._--Cephalis 0.01 long, 0.04 broad; thorax 0.12 long, 0.08
broad.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.


19. _Carpocanium irregulare_, n. sp. (Pl. 52, fig. 14).

Shell irregular, roundish, subovate, with flat and oblique, perfectly
hidden cephalis. Length of the two joints = 1 : 10, breadth = 3 : 9. Pores
irregularly scattered, roundish, about as broad as the bars. Mouth wide
open, not at all or little constricted. Peristome with twenty to thirty
long, lamellar, pointed feet, which are irregularly curved and convergent.

_Dimensions._--Cephalis 0.01 to 0.02 long, 0.03 to 0.04 broad; thorax 0.09
to 0.11 long, 0.08 to 0.09 broad.

_Habitat._--Central Pacific, Station 263 to 274, surface, and at various
depths.


20. _Carpocanium verecundum_, n. sp. (Pl. 52, figs. 12, 13).

Shell ovate, smooth, with flat, perfectly hidden cephalis (fig. 12). Length
of the two joints = 1 : 9, breadth = 4 : 9. Pores subregular, circular,
twice as broad as the bars, in about eighteen, {1285}partly interrupted,
longitudinal rows, separated by prominent crests. Mouth little constricted.
Peristome with twenty to twenty-four broad, lamellar, pointed feet, which
are about as long as the shell, little curved, and convergent.

_Dimensions._--Cephalis 0.01 long, 0.04 broad; thorax 0.09 long, 0.09
broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.


21. _Carpocanium virgineum_, n. sp. (Pl. 52, fig. 20).

Shell ovate, smooth, with flat perfectly hidden cephalis. Length of the two
joints = 1 : 8, breadth = 3 : 9. Pores regular, circular, hexagonally
framed, as broad as the bars, in about sixteen longitudinal rows on each
side. Mouth little constricted. Peristome with eighteen to twenty-four very
large, lamellar, pointed feet, which are longer than the shell, and so
curved and convergent that their distal points come nearly in contact.

_Dimensions._--Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.09
broad.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.



Subfamily 2. SETHOPHÆNIDA, Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Anthocyrtida# with the basal mouth of the shell fenestrated
(vel Dicyrtida multiradiata clausa).



Genus 570. _Sethophæna_,[187] Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Sethophænida# (vel Dicyrtida multiradiata clausa) with
lateral apophyses. Cephalis with a horn.

The genus _Sethophæna_ and the following _Clistophæna_ form together the
small subfamily of Sethophænida, comprising those Dicyrtida in which the
thorax bears numerous radial appendages (four to six or more), and the
mouth is closed by a lattice-plate. In _Sethophæna_ the apophyses are
lateral wings, as in _Micromelissa_, from which it may be derived by
development of secondary wings, interpolated between the three primary
wings.


1. _Sethophæna tetraptera_, n. sp.

Shell smooth, with deep collar stricture. Length of the two joints =
3 : 10, breadth = 4 : 9. Cephalis subspherical, without horn. Thorax ovate,
with rounded hemispherical base, and subregular, hexagonal pores. From its
upper half (below the collar stricture) arise four divergent,
{1286}conical, straight wings, of half the length, opposite in pairs in two
meridional planes, perpendicular to one another (compare _Tetralacorys_,
Pl. 65, figs. 4, 5).

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.09 broad.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.


2. _Sethophæna hexaptera_, n. sp. (Pl. 97, fig. 13).

Shell rough, pear-shaped, with distinct collar stricture. Length of the two
joints = 1 : 4, breadth = 2 : 4. Cephalis hemispherical, with a conical
horn of the same length. Thorax inflate, inversely ovate, nearly
pear-shaped, with subregular, circular pores. From its upper half arise, by
a broad base, six divergent, strong, conical wings, which are horn-like,
curved downwards, and half as long as the thorax.

_Dimensions._--Cephalis 0.025 long, 0.04 broad; thorax 0.09 long, 0.08
broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.


3. _Sethophæna enneaptera_, n. sp.

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 6,
breadth = 1 : 3. Cephalis subspherical, with a stout conical horn of twice
the length. Thorax inversely ovate, with pointed, conical, basal part, and
irregular, roundish pores. From its middle part arise, by a broad
triangular base, nine compressed, divergent wings, which are a little
curved, slender, and about as long as the thorax.

_Dimensions._--Cephalis 0.025 long, 0.03 broad; thorax 0.17 long, 0.1
broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.


4. _Sethophæna polyptera_, n. sp.

Shell thorny, with slight collar stricture. Length of the two joints =
1 : 10, breadth = 3 : 8. Cephalis flat, cap-shaped, without horn. Thorax
pear-shaped, with hemispherical base and regular, circular pores. From its
lower half (beyond the equator) arises a corona of numerous short conical
wings (eighteen to twenty-four), which are a little curved, and divergent
downwards, scarcely one-third as long as the thorax.

_Dimensions._--Cephalis 0.015 long, 0.04 broad; thorax 0.15 long, 0.12
broad.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.



Genus 571. _Clistophæna_,[188] Haeckel, 1881, Prodromus, p. 433.

_Definition._--#Sethophænida# (vel Dicyrtida multiradiata clausa) with
terminal apophyses. Cephalis with a horn.

{1287}The genus _Clistophæna_ agrees with the preceding _Sethophæna_ in the
mouth of the thorax being closed by a lattice-plate. But the appendages of
the thorax are terminal feet, not lateral wings; their number is commonly
six or nine, rarely more. _Clistophæna_ may be derived either from
_Tetrahedrina_ by interpolation of secondary feet between the three
primary, or from _Sethamphora_ by development of a basal lattice-plate
closing the mouth.


1. _Clistophæna rüstiana_, n. sp. (Pl. 57, fig. 6).

Shell rough, with distinct collar stricture. Length of the two joints =
3 : 10, breadth = 4 : 11. Cephalis hemispherical, with small, circular
pores and a stout oblique horn three times the length, which is three-sided
prismatic, and at the top denticulate. Thorax subconical, inflate, with
regular, circular, quincuncial pores, increasing in size towards the base.
Margin of the flat base, with six divergent, stout feet of the same
prismatic form as the cephalic horn, with denticulate distal ends, about as
long as the thorax. This elegant species is dedicated to Dr. Rüst of
Freiburg, the discoverer of numerous fossil Radiolaria in the Liassic and
Jurassic formations.

_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.11 broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.


2. _Clistophæna hexolena_, n. sp.

Shell smooth, with slight collar stricture. Length of the two joints =
1 : 4, breadth = 1 : 5. Cephalis subspherical, small, with a large